Publications by authors named "Enis Ozyar"

76 Publications

Stereotactic MR-guided online adaptive radiation therapy (SMART) for the treatment of liver metastases in oligometastatic patients: initial clinical experience.

Radiat Oncol J 2021 Mar 26;39(1):33-40. Epub 2021 Mar 26.

Department of Radiation Oncology, Acibadem Mehmet Ali Aydinlar University School of Medicine, Istanbul, Turkey.

Purpose: We aimed to present our initial clinical experience on the implementation of a stereotactic MR-guided online adaptive radiation therapy (SMART) for the treatment of liver metastases in oligometastatic disease.

Materials And Methods: Twenty-one patients (24 lesions) with liver metastasis treated with SMART were included in this retrospective study. Step-and-shoot intensity-modulated radiotherapy technique was used with daily plan adaptation. During delivery, real-time imaging was used by acquiring planar magnetic resonance images in sagittal plane for monitoring and gating. Acute and late toxicities were recorded both during treatment and follow-up visits.

Results: The median follow-up time was 11.6 months (range, 2.2 to 24.6 months). The median delivered total dose was 50 Gy (range, 40 to 60 Gy); with a median fraction number of 5 (range, 3 to 8 fractions) and the median fraction dose was 10 Gy (range, 7.5 to 18 Gy). Ninety-three fractions (83.7%) among 111 fractions were re-optimized. No patients were lost to follow-up and all patients were alive except one at the time of analysis. All of the patients had either complete (80.9%) or partial (19.1%) response at irradiated sites. Estimated 1-year overall survival was 93.3%. Intrahepatic and extrahepatic progression-free survival was 89.7% and 73.5% at 1 year, respectively. There was no grade 3 or higher acute or late toxicities experienced during the treatment and follow-up course.

Conclusion: SMART represents a new, noninvasive and effective alternative to current ablative radiotherapy methods for treatment of liver metastases in oligometastatic disease with the advantages of better visualization of soft tissue, real-time tumor tracking and potentially reduced toxicity to organs at risk.
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http://dx.doi.org/10.3857/roj.2020.00976DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8024184PMC
March 2021

Magnetic resonance image-guided stereotactic body radiation therapy for liver rhabdoid tumor in infancy: A case report.

J Med Imaging Radiat Sci 2021 Mar 16. Epub 2021 Mar 16.

Department of Radiation Oncology, Acibadem MAA University School of Medicine, Istanbul 34450, Turkey. Electronic address:

Extracranial malignant rhabdoid tumors are rare and aggressive tumors that typically occur in the pediatric age group and have a poor prognosis. Herein, we report a case of a one year and five months old male infant who was referred with the diagnosis of malignant rhabdoid tumor of the liver. Magnetic resonance guided stereotactic body radiotherapy was administered with concomitant chemotherapy. Treatment was well tolerated with no severe acute side effects. A 40.8% volumetric reduction of the tumor was observed at the last fraction of MR guided radiotherapy. Résumé: Les tumeurs rhabdoïdes malignes extracrâniennes sont des tumeurs rares et agressives qui surviennent généralement dans le groupe d'âge pédiatrique et dont le pronostic est mauvais. Nous rapportons ici le cas d'un enfant de sexe masculin d'un an et cinq mois qui a été référé avec le diagnostic de tumeur rhabdoïde maligne du foie. Une radiothérapie corporelle stéréotaxique guidée par résonance magnétique a été administrée avec une chimiothérapie concomitante. Le traitement a été bien toléré, sans effets secondaires aigus graves. Une réduction volumétrique de 40,8 % de la tumeur a été observée lors de la dernière fraction de la radiothérapie guidée par résonance magnétique.
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http://dx.doi.org/10.1016/j.jmir.2021.02.006DOI Listing
March 2021

International Recommendations on Reirradiation by Intensity Modulated Radiation Therapy for Locally Recurrent Nasopharyngeal Carcinoma.

Int J Radiat Oncol Biol Phys 2021 Jul 9;110(3):682-695. Epub 2021 Feb 9.

Department of Clinical Oncology, University of Hong Kong Shenzhen Hospital and University of Hong Kong, Hong Kong, China. Electronic address:

Purpose: Reirradiation for locally recurrent nasopharyngeal carcinoma (NPC) is challenging because prior radiation dose delivered in the first course is often close to the tolerance limit of surrounding normal structures. A delicate balance between achieving local salvage and minimizing treatment toxicities is needed. However, high-level evidence is lacking because available reports are mostly retrospective studies on small series of patients. Pragmatic consensus guidelines, based on an extensive literature search and the pooling of opinions by leading specialists, will provide a useful reference to assist decision-making for these difficult decisions.

Methods And Materials: A thorough review of available literature on recurrent NPC was conducted. A set of questions and preliminary draft guideline was circulated to a panel of international specialists with extensive experience in this field for voting on controversial areas and comments. A refined second proposal, based on a summary of the initial voting and different opinions expressed, was recirculated to the whole panel for review and reconsideration. The current guideline was based on majority voting after repeated iteration for final agreement.

Results: The initial round of questions showed variations in clinical practice even among the specialists, reflecting the lack of high-quality supporting data and the difficulties in formulating clinical decisions. Through exchange of comments and iterative revisions, recommendations with high-to-moderate agreement were formulated on general treatment strategies and details of reirradiation (including patient selection, targets contouring, dose prescription, and constraints).

Conclusion: This paper provides useful reference on radical salvage treatment strategies for recurrent NPC and optimization of reirradiation through review of published evidence and consensus building. However, the final decision by the attending clinician must include full consideration of an individual patient's condition, understanding of the delicate balance between risk and benefits, and acceptance of risk of complications.
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http://dx.doi.org/10.1016/j.ijrobp.2021.01.041DOI Listing
July 2021

Magnetic resonance image-guided adaptive stereotactic body radiotherapy for prostate cancer: preliminary results of outcome and toxicity.

Br J Radiol 2021 Jan 29;94(1117):20200696. Epub 2020 Oct 29.

Department of Radiation Oncology, Acıbadem MAA University School of Medicine, Istanbul, Turkey.

Objective: Using moderate or ultra-hypofractionation, which is also known as stereotactic body radiotherapy (SBRT) for treatment of localized prostate cancer patients has been increased. We present our preliminary results on the clinical utilization of MRI-guided adaptive radiotherapy (MRgRT) for prostate cancer patients with the workflow, dosimetric parameters, toxicities and prostate-specific antigen (PSA) response.

Methods: 50 prostate cancer patients treated with ultra-hypofractionation were included in the study. Treatment was performed with intensity-modulated radiation therapy (step and shoot) technique and daily plan adaptation using MRgRT. The SBRT consisted of 36.25 Gy in 5 fractions with a 7.25 Gy fraction size. The time for workflow steps was documented. Patients were followed for the acute and late toxicities and PSA response.

Results: The median follow-up for our cohort was 10 months (range between 3 and 29 months). The median age was 73.5 years (range between 50 and 84 years). MRgRT was well tolerated by all patients. Acute genitourinary (GU) toxicity rate of Grade 1 and Grade 2 was 28 and 36%, respectively. Only 6% of patients had acute Grade 1 gastrointestinal (GI) toxicity and there was no Grade ≥ 2 GI toxicity. To date, late Grade 1 GU toxicity was experienced by 24% of patients, 2% of patients experienced Grade 2 GU toxicity and 6% of patients reported Grade 2 GI toxicity. Due to the short follow-up, PSA nadir has not been reached yet in our cohort.

Conclusion: In conclusion, MRgRT represents a new method for delivering SBRT with markerless soft tissue visualization, online adaptive planning and real-time tracking. Our study suggests that ultra-hypofractionation has an acceptable acute and very low late toxicity profile.

Advances In Knowledge: MRgRT represents a new markerless method for delivering SBRT for localized prostate cancer providing online adaptive planning and real-time tracking and acute and late toxicity profile is acceptable.
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http://dx.doi.org/10.1259/bjr.20200696DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7774684PMC
January 2021

Magnetic Resonance-Guided Radiation Therapy to Boost Cervical Cancer When Brachytherapy Is Not Available: A Case Report.

Adv Radiat Oncol 2020 Sep-Oct;5(5):1066-1070. Epub 2020 Mar 10.

Department of Radiation Oncology, Mehmet Ali Aydınlar Acıbadem University, School of Medicine, Istanbul, Turkey.

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http://dx.doi.org/10.1016/j.adro.2020.02.009DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7557129PMC
March 2020

Risk of symptomatic radiation necrosis in patients treated with stereotactic radiosurgery for brain metastases.

Neurocirugia (Astur : Engl Ed) 2020 Oct 17. Epub 2020 Oct 17.

Department of Radiation Oncology, Acibadem Mehmet Ali Aydinlar University, School of Medicine, Istanbul, Turkey.

Introductio: Stereotactic radiosurgery (SRS) is a treatment option in the initial management of patients with brain metastases. While its efficacy has been demonstrated in several prior studies, treatment-related complications, particularly symptomatic radiation necrosis (RN), remains as an obstacle for wider implementation of this treatment modality. We thus examined risk factors associated with the development of symptomatic RN in patients treated with SRS for brain metastases.

Patients And Methods: We performed a retrospective review of our institutional database to identify patients with brain metastases treated with SRS. Diagnosis of symptomatic RN was determined by appearance on serial MRIs, MR spectroscopy, requirement of therapy, and the development of new neurological complaints without evidence of disease progression.

Results: We identified 323 brain metastases treated with SRS in 170 patients from 2009 to 2018. Thirteen patients (4%) experienced symptomatic RN after treatment of 23 (7%) lesions. After SRS, the median time to symptomatic RN was 8.3 months. Patients with symptomatic RN had a larger mean target volume (p<0.0001), and thus larger V100% (p<0.0001), V50% (p<0.0001), V12Gy (p<0.0001), and V10Gy (p=0.0002), compared to the rest of the cohort. Single-fraction treatment (p=0.0025) and diabetes (p=0.019) were also significantly associated with symptomatic RN.

Conclusion: SRS is an effective treatment option for patients with brain metastases; however, a subset of patients may develop symptomatic RN. We found that patients with larger tumor size, larger plan V100%, V50%, V12Gy, or V10Gy, who received single-fraction SRS, or who had diabetes were all at higher risk of symptomatic RN.
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http://dx.doi.org/10.1016/j.neucir.2020.08.009DOI Listing
October 2020

Patient-Reported Tolerance of Magnetic Resonance-Guided Radiation Therapy.

Front Oncol 2020 21;10:1782. Epub 2020 Sep 21.

Department of Radiation Oncology, School of Medicine, Mehmet Ali Aydınlar Acıbadem University, Istanbul, Turkey.

Purpose: Magnetic resonance-guided radiation therapy (MRgRT) has been incorporated into a growing number of clinical practices world-wide, however, there is limited data on patient experiences with MRgRT. The purpose of this study was to prospectively evaluate patient tolerance of MRgRT using patient reported outcome questionnaires (PRO-Q).

Methods: Ninety patients were enrolled in this prospective observational study and treated with MRgRT (MRIdian Linac System, ViewRay Inc. Oakwood Village, OH, United States) between September 2018 and September 2019. Breath-hold-gated dose delivery with audiovisual feedback was completed as needed. Patients completed an in-house developed PRO-Q after the first and last fraction of MRgRT.

Results: The most commonly treated anatomic sites were the abdomen (47%) and pelvis (33%). Respiratory gating was utilized in 62% of the patients. Patients rated their experience as positive or at least tolerable with mean scores of 1.0-2.8. The most common complaint was the temperature in the room (61%) followed by paresthesias (57%). The degree of anxiety reported by 45% of the patients significantly decreased at the completion of treatment (mean score 1.54 vs. 1.36, = 0.01). Forty-three percent of the patients reported some degree of disturbing noise which was improved considerably by use of music. All patients appreciated their active role during the treatment.

Conclusion: This evaluation of PROs indicates that MRgRT was well-tolerated by our patients. Patients' experience may further improve with adjustment of room temperature and noise reduction.
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http://dx.doi.org/10.3389/fonc.2020.01782DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7537416PMC
September 2020

Management of symptomatic radiation necrosis after stereotactic radiosurgery and clinical factors for treatment response.

Radiat Oncol J 2020 Sep 14;38(3):176-180. Epub 2020 Jul 14.

Institute of Health Sciences, Mehmet Ali Aydinlar Acibadem University, Istanbul, Turkey.

Purpose: Approximately 10% of patients who received brain stereotactic radiosurgery (SRS) develop symptomatic radiation necrosis (RN). We sought to determine the effectiveness of treatment options for symptomatic RN, based on patient-reported outcomes.

Materials And Methods: We conducted a retrospective review of 217 patients with 414 brain metastases treated with SRS from 2009 to 2018 at our institution. Symptomatic RN was determined by appearance on serial magnetic resonance images (MRIs), MR spectroscopy, requirement of therapy, and development of new neurological complaints without evidence of disease progression. Therapeutic interventions for symptomatic RN included corticosteroids, bevacizumab and/or surgical resection. Patient-reported therapeutic outcomes were graded as complete response (CR), partial response (PR), and no response.

Results: Twenty-six patients experienced symptomatic RN after treatment of 50 separate lesions. The mean prescription dose was 22 Gy (range, 15 to 30 Gy) in 1 to 5 fractions (median, 1 fraction). Of the 12 patients managed with corticosteroids, 6 patients (50%) reported CR and 4 patients (33%) PR. Of the 6 patients managed with bevacizumab, 3 patients (50%) reported CR and 1 patient (18%) PR. Of the 8 patients treated with surgical resection, all reported CR (100%). Other than surgical resection, age ≥54 years (median, 54 years; range, 35 to 81 years) was associated with CR (odds ratio = 8.40; 95% confidence interval, 1.27-15.39; p = 0.027).

Conclusion: Corticosteroids and bevacizumab are commonly utilized treatment modalities with excellent response rate. Our results suggest that patient's age is associated with response rate and could help guide treatment decisions for unresectable symptomatic RN.
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http://dx.doi.org/10.3857/roj.2020.00171DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7533401PMC
September 2020

Prognostic factors in medically inoperable early stage lung cancer patients treated with stereotactic ablative radiation therapy (SABR): Turkish Radiation Oncology Society Multicentric Study.

Clin Respir J 2020 Nov 17;14(11):1050-1059. Epub 2020 Aug 17.

Faculty of Medicine, Radiation Oncology Department, Ankara University, Ankara, Turkey.

Objective: We identified factors influencing outcomes in patients with medically inoperable early stage lung cancer (MIESLC) treated with stereotactic ablative radiation therapy (SABR) at 14 centers in Turkey.

Materials And Methods: We retrospectively analyzed 431 patients with stage I-II MIESLC treated with SABR from 2009 through 2017. Age; sex; performance score; imaging technique; tumor histology and size; disease stage radiation dose, fraction and biologically effective dose with an α/β ratio of 10 (BED ); tumor location and treatment center were evaluated for associations with overall survival (OS), local control (LC) and toxicity.

Results: Median follow-up time was 27 months (range 1-115); median SABR dose was 54 Gy (range 30-70) given in a median three fractions (range 1-10); median BED was 151 Gy (range 48-180). Tumors were peripheral in 285 patients (66.1%), central in 69 (16%) and <1 cm from mediastinal structures in 77 (17.9%). Response was evaluated with PET/CT in most cases at a median 3 months after SABR. Response rates were: 48% complete, 36.7% partial, 7.9% stable and 7.4% progression. LC rates were 97.1% at 1 year, 92.6% at 2 years and 91.2% at 3 years; corresponding OS rates were 92.6%, 80.6% and 72.7%. On multivariate analysis, BED > 100 Gy (P = .011), adenocarcinoma (P = .025) and complete response on first evaluation (P = .007) predicted favorable LC. BED > 120 Gy (hazard ratio [HR] 1.9, 95% confidence interval [CI] 1.1-3.2, P = .019) and tumor size (<2 cm HR 1.9, 95% CI 1.3-3, P = .003) predicted favorable OS. No grade 4-5 acute side effects were observed; late effects were grade ≤3 pneumonitis (18 [4.2%]), chest wall pain (11 [2.5%]) and rib fracture (1 [0.2%]).

Conclusion: SABR produced encouraging results, with satisfactory LC and OS and minimal toxicity. BED > 120 Gy was needed for better LC and OS for large, non-adenocarcinoma tumors.
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http://dx.doi.org/10.1111/crj.13240DOI Listing
November 2020

Time Analysis of Online Adaptive Magnetic Resonance-Guided Radiation Therapy Workflow According to Anatomical Sites.

Pract Radiat Oncol 2021 Jan-Feb;11(1):e11-e21. Epub 2020 Jul 30.

Department of Radiation Oncology, Acıbadem University School of Medicine, Istanbul, Turkey.

Purpose: To document time analysis of detailed workflow steps for the online adaptive magnetic resonance-guided radiation therapy treatments (MRgRT) with the ViewRay MRIdian system and to identify the barriers to and solutions for shorter treatment times.

Methods And Materials: A total of 154 patients were treated with the ViewRay MRIdian system between September 2018 and October 2019. The time process of MRgRT workflow steps of 962 fractions for 166 treatment sites was analyzed in terms of patient and online adaptive treatment (ART) characteristics.

Results: Overall, 774 of 962 fractions were treated with online ART, and 83.2% of adaptive fractions were completed in less than 60 minutes. Sixty-three percent, 50.3%, and 4.2% of fractions were completed in less than 50 minutes, 45 minutes, and 30 minutes, respectively. Eight-point-three percent and 3% of fractions were completed in more than 70 minutes and 80 minutes, respectively. The median time (t) for ART workflow steps were as follows: (1) setup t: 5.0 minutes, (2) low-resolution scanning t: 1 minute, (3) high-resolution scanning t: 3 minutes, (4) online contouring t: 9 minutes, (5) reoptimization with online quality assurance t: 5 minutes, (6) real targeting t: 3 minutes, (7) beam delivery with gating t: 17 minutes, and (8) net total treatment time t: 45 minutes. The shortest and longest t rates of net total treatment time were 41.59 minutes and 64.43 minutes for upper-lung-lobe-located thoracic tumors and ultracentrally located thoracic tumors, respectively.

Conclusions: To our knowledge, this is the first broad treatment-time analysis for online ART in the literature. Although treatment times are long due to human- and technology-related limitations, benefits offered by MRgRT might be clinically important. In the future, implementation of artificial intelligence segmentation, an increase in dose rate, and faster multileaf collimator and gantry speeds may lead to achieving shorter MRgRT treatments.
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http://dx.doi.org/10.1016/j.prro.2020.07.003DOI Listing
July 2020

Long-term toxicity and survival outcomes after stereotactic ablative radiotherapy for patients with centrally located thoracic tumors.

Radiol Oncol 2020 06 26;54(4):480-487. Epub 2020 Jun 26.

Department of Radiation Oncology, Acibadem MAA University, Istanbul, Turkey.

Background Stereotactic ablative radiotherapy (SABR) is effective for thoracic cancer and metastases; however, adverse effects are greater for central tumors. We evaluated factors affecting outcomes and toxicities after SABR for patients with primary lung and oligometastatic tumors. Patients and methods We retrospectively identified consecutive patients with centrally located lung tumors that were treated at our hospital from 2009-2016. The effects of patient, disease, and treatment-related parameters on local control (LC), overall survival (OS), and toxicity-free survival (TFS) were evaluated with multivariate analyses. Results Among 65 consecutive patients identified with 70 centrally located tumors, 20 tumors (28%) were reirradiated. Median (range) total dose for all tumors was 55 (30-60) Gy in 5 (3-10) fractions. Radiographic complete response was obtained in 43 lesions (61%). None of the analyzed factors were correlated with complete response. After a median follow-up of 57 (95% CI, 48-65) months, 10 tumors (14%) relapsed and 37 patients (57%) died; the actuarial 2- and 5-year OS rates were 52% and 28%, respectively. Median OS was significantly lower in patients with grade 3 or higher toxicity vs. lower toxicity (5 vs. 39 months; P < 0.001). Among 17 severe toxicities, 5 were grade 5, and 3 of them were reirradiated to the same field. Grade 3 to 5 TFS was lower with vs. without reirradiation (2-year TFS, 63% vs. 96%; P = 0.02). Conclusions Our study showed that modern SABR is effective for central lung tumors, and toxicities are acceptable. SABR for reirradiated central lung lesions and possibly for lesions abutting the tracheobronchial tree may result in higher risk of serious toxicities.
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http://dx.doi.org/10.2478/raon-2020-0039DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7585334PMC
June 2020

Multichannel Film Dosimetry for Quality Assurance of Intensity Modulated Radiotherapy Treatment Plans Under 0.35 T Magnetic Field.

Cureus 2020 Mar 20;12(3):e7334. Epub 2020 Mar 20.

Radiation Oncology, Acıbadem Hospital, Istanbul, TUR.

Purpose To evaluate the intensity modulated radiotherapy (IMRT) quality assurance (QA) results of the multichannel film dosimetry analysis with single scan method by using Gafchromic™ EBT3 (Ashland Inc., Covington, KY, USA) film under 0.35 T magnetic field. Methods Between September 2018 and June 2019, 70 patients were treated with ViewRay MRIdian (ViewRay Inc., Mountain View, CA) linear accelerator (Linac). Film dosimetry QA plans were generated for all IMRT treatments. Multichannel film dosimetry for red, green and blue (RGB) channels were compared with treatment planning system (TPS) dose maps by gamma evaluation analysis. Results The mean gamma passing rates of RGB channels are 97.3% ± 2.26%, 96.0% ± 3.27% and 96.2% ± 3.14% for gamma evaluation with 2% DD/2 mm distance to agreement (DTA), respectively. Moreover, the mean gamma passing rates of RGB channels are 99.7% ± 0.41%, 99.6% ± 0.59% and 99.5% ± 0.67% for gamma evaluation with 3% DD/3 mm DTA, respectively. Conclusion The patient specific QA using Gafchromic™ EBT3 film with multichannel film dosimetry seems to be a suitable tool to implement for MR-guided IMRT treatments under 0.35 T magnetic field. Multichannel film dosimetry with Gafchromic™ EBT3 is a consistent QA tool for gamma evaluation of the treatment plans even with 2% DD/2 mm DTA under 0.35 T magnetic field presence.
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http://dx.doi.org/10.7759/cureus.7334DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7164695PMC
March 2020

First 500 Fractions Delivered with a Magnetic Resonance-guided Radiotherapy System: Initial Experience.

Cureus 2019 Dec 24;11(12):e6457. Epub 2019 Dec 24.

Radiation Oncology, Acibadem University School of Medicine, Acibadem Maslak Hospital, Istanbul, TUR.

Objectives Improved soft-tissue visualization, afforded by magnetic resonance imaging integrated into a radiation therapy linear accelerator-based radiation delivery system (MR-linac) promises improved image-guidance. The availability of MR-imaging can facilitate on-table adaptive radiation planning and enable real-time intra-fraction imaging with beam gating without additional exposure to radiation. However, the novel use of magnetic resonance-guided radiation therapy (MRgRT) in the field of radiation oncology also potentially poses challenges for routine clinical implementation. Herein the early experience of a single institution, implementing the first MRgRT system in the country is reported. We aim to describe the workflow and to characterize the clinical utility and feasibility of routine use of an MR-linac system. Methods The ViewRay MRIdian MR-linac system consists of a split-magnet 0.35 T MR-imaging scanner with a double focused multi-leaf collimator (MLC) equipped 6MV linear accelerator. Unique to the system are the control console integrated on-table adaptive radiation therapy (oART) planning capabilities as well as automated beam gating based on real-time intra-fraction MR imaging. From the first day of clinical implementation, oART was performed according to physicians' discretion when medically indicated. All fractions were delivered under real-time imaging with soft tissue-based automated beam gating with individualized gating boundary settings. Patients actively assisted in breath-hold beam gating with the help of custom designed prismatic glasses allowing sight of a computer monitor mounted on the back wall just behind the MRI system bore. Patient demographics and treatment experience, indications for MRgRT including diagnosis and disease site, radiation dose prescribed and fractionation scheme, utilization of oART, respiratory gating settings, as well as duration of each treatment phase were analyzed. Results Between September 2018 and May 2019, 72 patients with 84 tumor sites were treated with MRgRT in 500 total fractions. Median patient age was 66 years (range: 28-83 years). Among 84 tumor sites, the most frequently treated regions were upper abdominal and pelvic (n = 36, 43% and n = 29, 34%, respectively). The most common diagnosis was prostate cancer, with 14 patients treated. In 69 patients (93.2%) oART was used at least once during a treatment course. Twenty-nine targets (43.1%) with significant breathing-related motion were treated in breath-hold with patient visual feedback. Median prescribed dose was 36.25 Gy (range: 24-70 Gy) in median five fractions (range: 3-28 fractions). A gating boundary of 3 mm around a gating region of interest (gROI) was most commonly used (range: 3-5 mm) with 95% of the gROI (range: 93-97%) required to be within the gating boundary for the beam to automatically engage. Mean total treatment time was 47 min (range: 21-125 min) and mean beam-on time was 16.7 min (range: 6-62 min). Conclusions MRgRT afforded by an MR-linac system has been successfully implemented into routine clinical use at our institution as the first system of its kind in Turkey. While the overall number of patients treated and fractions delivered is still limited, we have demonstrated the feasibility of both on-table adaptive radiation therapy as well as automated real-time beam gating on a daily basis in acceptable time schedules.
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http://dx.doi.org/10.7759/cureus.6457DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6977582PMC
December 2019

The impact of total neo-adjuvant treatment on nonoperative management in patients with locally advanced rectal cancer: The evaluation of 66 cases.

Eur J Surg Oncol 2020 03 8;46(3):402-409. Epub 2019 Jul 8.

Acibadem University Maslak Hospital, Radiology, Istanbul, Turkey. Electronic address:

Background: The study aimed to assess if adherence to a total-neoadjuvant-treatment (TNT) protocol followed by observation(watch-and-wait) led to the successful nonoperative-management of low-rectal-cancer.

Methods: In this study, patients with primary, resectable-T3-T4, N0-N1 distal-rectal-adenocarcinoma underwent-chemoradiotherapy + consolidation-chemotherapy (TNT). During the-TNT-period, endoscopy, MRI, and FDG-PET/CT were performed. We allocated patients with complete-clinical-tumor-regression, who underwent endoscopy every two months, MRI every-four-months, and PET/CT every-six-months-after-treatment, to the observation-group(OG). All other patients were referred for surgery. The OG was followed-up. The primary endpoint was local tumor-ecurrence after allocation to the OG.

Results: Between 2015 and 2018, we enrolled 66-patients. Of 60-patients who were eligible to participate, 39 had complete-clinical-response(cCR) and were allocated to the OG, six underwent local-excision (LE), and 15 underwent total-mesorectal-excision (TME). The median follow-up duration was 22 (9-42) months. The local-recurrence-rate in the OG was 15.3%, and the LE and TME rates were 16.6% and 0%, respectively. All recurrence cases were salvaged through either LE or TME. The-distant-metastasis rate was 5.1%, 16.6%, and 12.5% in the OG, LE, and TME groups, respectively. The endoscopic negative-predictive-value(NPV) was 50%, and the positive-predictive-value(PPV) was 76.9% in the surgery group (LE + TME). MRI; NPV-50%, PPV-76.9%. PET/CT; NPV-100%, PPV-93.3%. Six patients(28.57%) from surgery group achieved complete pathological response (cPR).

Conclusion: Our results indicated a high proportion of selected-rectal-cancers with-cCR after neo-adjuvant-therapy could potentially be managed non-operatively, and major surgery may be avoided.
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http://dx.doi.org/10.1016/j.ejso.2019.07.012DOI Listing
March 2020

Evaluation of response to stereotactic radiosurgery in patients with radioresistant brain metastases.

Radiat Oncol J 2019 Dec 31;37(4):265-270. Epub 2019 Dec 31.

Department of Radiation Oncology, School of Medicine, Mehmet Ali Aydinlar Acibadem University, Istanbul, Turkey.

Purpose: Renal cell carcinoma (RCC) and melanoma have been considered 'radioresistant' due to the fact that they do not respond to conventionally fractionated radiation therapy. Stereotactic radiosurgery (SRS) provides high-dose radiation to a defined target volume and a limited number of studies have suggested the potential effectiveness of SRS in radioresistant histologies. We sought to determine the effectiveness of SRS for the treatment of patients with radioresistant brain metastases.

Materials And Methods: We performed a retrospective review of our institutional database to identify patients with RCC or melanoma brain metastases treated with SRS. Treatment response were determined in accordance with the Response Evaluation Criteria in Solid Tumors.

Results: We identified 53 radioresistant brain metastases (28% RCC and 72% melanoma) treated in 18 patients. The mean target volume and coverage was 6.2 ± 9.5 mL and 95.5% ± 2.9%, respectively. The mean prescription dose was 20 ± 4.9 Gy. Forty lesions (75%) demonstrated a complete/partial response and 13 lesions (24%) with progressive/stable disease. Smaller target volume (p < 0.001), larger SRS dose (p < 0.001), and coverage (p = 0.008) were found to be positive predictors of complete response to SRS.

Conclusion: SRS is an effective management option with up to 75% response rate for radioresistant brain metastases. Tumor volume and radiation dose are predictors of response and can be used to guide the decision-making for patients with radioresistant brain metastases.
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http://dx.doi.org/10.3857/roj.2019.00409DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6952719PMC
December 2019

Strahlentherapie bei Brustkrebs löst kutanen Lupus erythematodes aus.

J Dtsch Dermatol Ges 2019 Aug;17(8):832-833

Department of Pathology, Acıbadem Mehmet Ali Aydınlar University School of Medicine, Istanbul, Turkey.

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http://dx.doi.org/10.1111/ddg.13888_gDOI Listing
August 2019

Cutaneous lupus erythematosus induced by radiotherapy for breast carcinoma.

J Dtsch Dermatol Ges 2019 08 15;17(8):832-833. Epub 2019 Jul 15.

Department of Pathology, Acıbadem Mehmet Ali Aydınlar University School of Medicine, Istanbul, Turkey.

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http://dx.doi.org/10.1111/ddg.13888DOI Listing
August 2019

International Guideline on Dose Prioritization and Acceptance Criteria in Radiation Therapy Planning for Nasopharyngeal Carcinoma.

Int J Radiat Oncol Biol Phys 2019 11 2;105(3):567-580. Epub 2019 Jul 2.

Division of Radiation Oncology, National Cancer Centre Singapore, Oncology ACP, Duke-NUS Medical School, Singapore. Electronic address:

Purpose: The treatment of nasopharyngeal carcinoma requires high radiation doses. The balance of the risks of local recurrence owing to inadequate tumor coverage versus the potential damage to the adjacent organs at risk (OARs) is of critical importance. With advancements in technology, high target conformality is possible. Nonetheless, to achieve the best possible dose distribution, optimal setting of dose targets and dose prioritization for tumor volumes and various OARs is fundamental. Radiation doses should always be guided by the As Low As Reasonably Practicable principle. There are marked variations in practice. This study aimed to develop a guideline to serve as a global practical reference.

Methods And Materials: A literature search on dose tolerances and normal-tissue complications after treatment for nasopharyngeal carcinoma was conducted. In addition, published guidelines and protocols on dose prioritization and constraints were reviewed. A text document and preliminary set of variants was circulated to a panel of international experts with publications or extensive experience in the field. An anonymized voting process was conducted to rank the proposed variants. A summary of the initial voting and different opinions expressed by members were then recirculated to the whole panel for review and reconsideration. Based on the comments of the panel, a refined second proposal was recirculated to the same panel. The current guideline was based on majority voting after repeated iteration for final agreement.

Results: Variation in opinion among international experts was repeatedly iterated to develop a guideline describing appropriate dose prioritization and constraints. The percentage of final agreement on the recommended parameters and alternative views is shown. The rationale for the recommendations and the limitations of current evidence are discussed.

Conclusions: Through this comprehensive review of available evidence and interactive exchange of vast experience by international experts, a guideline was developed to provide a practical reference for setting dose prioritization and acceptance criteria for tumor volumes and OARs. The final decision on the treatment prescription should be based on the individual clinical situation and the patient's acceptance of optimal balance of risk.
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http://dx.doi.org/10.1016/j.ijrobp.2019.06.2540DOI Listing
November 2019

Paraganglioma of the head and neck region, treated with radiation therapy, a Rare Cancer Network study.

Head Neck 2019 06 11;41(6):1770-1776. Epub 2019 Jan 11.

Radiation Oncology Department, Centre Francois Baclesse, Caen, France.

Background: Paraganglioma of the head and neck (HNPGL) are rare often benign tumors. Surgery and radiation therapy (RT) are the main treatment choices. We present an analysis of outcome and toxicity after RT from 13 institutions of the Rare Cancer Network.

Methods: Data were collected using a questionnaire concerning patients' characteristics, treatment, and outcome. A total of 81 patients with 82 HNPGL were analyzed.

Results: The median follow-up was 48 months (1-456). Sixty-two lesions were treated with conventional RT and 20 lesions with stereotactic RT. Local control (LC) was achieved in 69 out of 77 lesions. Late toxicity occurred in 17 patients. Patients treated with stereotactic RT experienced neither disease progression nor late toxicity. Four patients with a follow-up longer than 20 years experienced disease progression.

Conclusion: RT for HNPGL offered good local control with acceptable toxicity. Stereotactic RT might offer better results. Long-term follow-up is required.
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http://dx.doi.org/10.1002/hed.25611DOI Listing
June 2019

Output factors of ionization chambers and solid state detectors for mobile intraoperative radiotherapy (IORT) accelerator electron beams.

J Appl Clin Med Phys 2019 Feb 10;20(2):13-23. Epub 2019 Jan 10.

Department of Radiation Oncology, Acıbadem Mehmet Ali Aydınlar University School of Medicine, Istanbul, Turkey.

Purpose: The electron energy characteristics of mobile intraoperative radiotherapy (IORT) accelerator LIAC differ from commonly used linear accelerators, thus some of the frequently used detectors can give less accurate results. The aim of this study is to evaluate the output factors (OFs) of several ionization chambers (IC) and solid state detectors (SS) for electron beam energies generated by LIAC and compare with the output factor of Monte Carlo model (MC) in order to determine the adequate detectors for LIAC .

Methods: The OFs were measured for 6, 8, 10, and 12 MeV electron energies with PTW 23343 Markus, PTW 34045 Advanced Markus, PTW 34001 Roos, IBA PPC05, IBA PPC40, IBA NACP-02, PTW 31010 Semiflex, PTW 31021 Semiflex 3D, PTW 31014 Pinpoint, PTW 60017 Diode E, PTW 60018 Diode SRS, SNC Diode EDGE, and PTW 60019 micro Diamond detectors. Ion recombination factors (k ) of IC were measured for all applicator sizes and OFs were corrected according to k . The measured OFs were compared with Monte Carlo output factors (OF ).

Results: The measured OFs of IBA PPC05, PTW Advanced Markus, PTW Pinpoint, PTW microDiamond, and PTW Diode E detectors are in good agreement with OF . The maximum deviations of IBA PPC05 OFs to OF are -1.6%, +1.5%, +1.5%, and +2.0%; for PTW Advanced Markus +1.0%, +1.5%, +2.0%, and +2.0%; for PTW Pinpoint +2.0%, +1.6%, +4.0%, and +2.0%; for PTW microDiamond -1.6%, +2%, +1.1%, and +1.0%; and for PTW Diode E -+1.7%, +1.7%, +1.3%, and +2.5% for 6, 8, 10, and 12 MeV, respectively. PTW Roos, PTW Markus, IBA PPC40, PTW Semiflex, PTW Semiflex 3D, SNC Diode Edge measured OFs with a maximum deviation of +5.6%, +4.5%, +5.6%, +8.1%, +4.8%, and +9.6% with respect to OF , while PTW Diode SRS and IBA NACP-02 were the least accurate (with highest deviations -37.1% and -18.0%, respectively).

Conclusion: The OFs results of solid state detectors PTW microDiamond and PTW Diode E as well as the ICs with small electrode spacing distance such as IBA PPC05, PTW Advanced Markus and PTW Pinpoint are in excellent agreement with OF . The measurements of the other detectors evaluated in this study are less accurate, thus they should be used with caution. Particularly, PTW Diode SRS and IBA NACP-02 are not suitable and their use should be avoided in relative dosimetry measurements under high dose per pulsed (DPP) electron beams.
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http://dx.doi.org/10.1002/acm2.12522DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6370992PMC
February 2019

Dealing with the gray zones in the management of gastric cancer: The consensus statement of the İstanbul Group.

Turk J Gastroenterol 2019 Jul;30(7):584-598

Acıbadem Mehmet Ali Aydınlar University School of Medicine, İstanbul, Turkey.

The geographical location and differences in tumor biology significantly change the management of gastric cancer. The prevalence of gastric cancer ranks fifth and sixth among men and women, respectively, in Turkey. The international guidelines from the Eastern and Western countries fail to manage a considerable amount of inconclusive issues in the management of gastric cancer. The uncertainties lead to significant heterogeneities in clinical practice, lack of homogeneous data collection, and subsequently, diverse outcomes. The physicians who are professionally involved in the management of gastric cancer at two institutions in Istanbul, Turkey, organized a consensus meeting to address current problems and plan feasible, logical, measurable, and collective solutions in their clinical practice for this challenging disease. The evidence-based data and current guidelines were reviewed. The gray zones in the management of gastric cancer were determined in the first session of this consensus meeting. The second session was constructed to discuss, vote, and ratify the ultimate decisions. The identification of the T stage, the esophagogastric area, imaging algorithm for proper staging and follow-up, timing and patient selection for neoadjuvant treatment, and management of advanced and metastatic disease have been accepted as the major issues in the management of gastric cancer. The recommendations are presented with the percentage of supporting votes in the results section with related data.
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http://dx.doi.org/10.5152/tjg.2018.18737DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6629281PMC
July 2019

In Regard to Wortel et al.

Int J Radiat Oncol Biol Phys 2018 04;100(5):1291

Department of Radiation Oncology, Acıbadem University School of Medicine, Istanbul, Turkey.

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http://dx.doi.org/10.1016/j.ijrobp.2017.12.283DOI Listing
April 2018

Non-small Cell Lung Cancer with Multiple Brain Metastases Treated with Radiosurgery and Erlotinib: A Case Report.

Cureus 2017 Dec 29;9(12):e2003. Epub 2017 Dec 29.

Radiation Oncology, Acibadem University Acibabem Maslak Hospital, Turkey.

Brain metastases are commonly seen complications in non-small cell lung cancer (NSCLC) patients. The incidence of brain metastases is increasing as a result of more effective systemic targeted therapies with prolonged survival. The prognosis is usually poor, and up to six months of median survivals were reported with different therapeutic options. Here, we present an NSCLC case with multiple brain metastases treated with radiosurgery and systemic erlotinib therapy with prolonged survival. The use of tyrosine kinase inhibitors (TKI) in conjunction with either stereotactic radiosurgery or whole brain radiotherapy is not well established in terms of efficiency and toxicity. This reported case had an excellent response with a tolerable toxicity profile from the combination of either therapies.
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http://dx.doi.org/10.7759/cureus.2003DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5832407PMC
December 2017

Treatment outcome and prognostic factors for adult patients with medulloblastoma: The Rare Cancer Network (RCN) experience.

Radiother Oncol 2018 Apr 17;127(1):96-102. Epub 2018 Jan 17.

Department of Radiation Oncology, Mayo Clinic Hospital, Phoenix, AZ, United States.

Background And Purpose: The optimal treatment for adults with newly diagnosed medulloblastoma (MB) has not been defined. We report a large series of cases from the Rare Cancer Network.

Material And Methods: Thirteen institutions enrolled 206 MB patients who underwent postoperative radiotherapy (RT) between 1976 and 2014. Log-rank univariate and Cox-modeled multivariate analyses were used to analyze data collected.

Results: Median patient age was 29 years; follow-up was 31 months. All patients had the tumor resected; surgery was complete in 140 (68%) patients. Postoperative RT was given in 202 (98%) patients, and 94% received craniospinal irradiation (CSI) and, usually, a posterior fossa boost. Ninety-eight (48%) patients had chemotherapy, mostly cisplatin and vincristine-based. The 10-year local control, overall survival, and disease-free survival rates were 46%, 51%, and 38%, respectively. In multivariate analyses, Karnofsky Performance Status (KPS) ≥80 and CSI were significant for disease-free and overall survival (P ≤ .04 for all); receiving chemotherapy and KPS ≥80 correlated with better local-control rates.

Conclusions: Patients with high KPS who received CSI had better rates of disease-free and overall survival. Chemotherapy was associated with better local control. These results may serve as a benchmark for future studies designed to improve outcomes for adults with medulloblastoma.
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http://dx.doi.org/10.1016/j.radonc.2017.12.028DOI Listing
April 2018

Improvement of conformal arc plans by using deformable margin delineation method for stereotactic lung radiotherapy.

J Appl Clin Med Phys 2018 Jan 7;19(1):184-193. Epub 2017 Dec 7.

Department of Radiation Oncology, Acıbadem University School of Medicine, Istanbul, Turkey.

Purpose: Stereotactic body radiotherapy (SBRT) is an established treatment technique in the management of medically inoperable early stage non-small cell lung cancer (NSCLC). Different techniques such as volumetric modulated arc (VMAT) and three-dimensional conformal arc (DCA) can be used in SBRT. Previously, it has been shown that VMAT is superior to DCA technique in terms of plan evaluation parameters. However, DCA technique has several advantages such as ease of use and considerable shortening of the treatment time. DCA technique usually results in worse conformity which is not possible to ameliorate by inverse optimization. In this study, we aimed to analyze whether a simple method - deformable margin delineation (DMD) - improves the quality of the DCA technique, reaching similar results to VMAT in terms of plan evaluation parameters.

Methods: Twenty stage I-II (T1-2, N0, M0) NSCLC patients were included in this retrospective dosimetric study. Noncoplanar VMAT and conventional DCA plans were generated using 6 MV and 10 MV with flattening filter free (FFF) photon energies. The DCA plan with 6FFF was calculated and 95% of the PTV was covered by the prescription isodose line. Hot dose regions (receiving dose over 100% of prescription dose) outside PTV and cold dose regions (receiving dose under 100% of prescription dose) inside PTV were identified. A new PTV (PTV-DMD) was delineated by deforming PTV margin with respect to hot and cold spot regions obtained from conventional DCA plans. Dynamic multileaf collimators (MLC) were set to PTV-DMD beam eye view (BEV) positions and the new DCA plans (DCA-DMD) with 6FFF were generated. Three-dimensional (3D) dose calculations were computed for PTV-DMD volume. However, the prescription isodose was specified and normalized to cover 95% volume of original PTV. Several conformity indices and lung doses were compared for different treatment techniques.

Results: DCA-DMD method significantly achieved a superior conformity index (CI), conformity number (CI ), gradient index (R ), isodose at 2 cm (D ) and external index (CΔ) with respect to VMAT and conventional DCA plans (P < 0.05 for all comparisons). CI ranged between 1.00-1.07 (Mean: 1.02); 1.00-1.18 (Mean: 1.06); 1.01-1.23 (Mean 1.08); 1.03-1.29 (Mean: 1.15); 1.04-1.29 (Mean: 1.18) for DCA-DMD-6FFF, VMAT-6FFF, VMAT-10FFF DCA-6FFF and DCA-10FFF respectively. DCA-DMD-6FFF technique resulted significantly better CI compared to others (P = 0.002; < 0.001; < 0.001; < 0.001). R ranged between 3.22-4.74 (Mean: 3.99); 3.24-5.92 (Mean: 4.15) for DCA-DMD-6FFF, VMAT-6FFF, respectively. DCA-DMD-6FFF technique resulted lower intermediate dose spillage compared to VMAT-6FFF, though the difference was statistically insignificant (P = 0.32). D ranged between 35.7% and 67.0% (Mean: 53.2%); 42.1%-79.2% (Mean: 57.8%) for DCA-DMD-6FFF, VMAT-6FFF respectively. DCA-DMD-6FFF have significantly better and sharp falloff gradient 2 cm away from PTV compared to VMAT-6FFF (P = 0.009). CΔ ranged between 0.052 and 0.140 (Mean: 0.085); 0,056-0,311 (Mean: 0.120) for DCA-DMD, VMAT-6FFF, respectively. DCA-DMD-6FFF have significantly improved CΔ (P = 0.002). VMAT- V , V and mean lung dose (MLD) indices are calculated to be 4.03%, 23.83%, 3.42 Gy and 4.19%, 27.88%,3.72 Gy, for DCA-DMD-6FFF and DCA techniques, respectively. DCA-DMD-6FFF achieved superior lung sparing compared to DCA technique. DCA-DMD-6FFF method reduced MUs 44% and 33% with respect to VMAT-6FFF and 10FFF, respectively, without sacrificing dose conformity (P < 0.001; P < 0.001).

Conclusions: Our results demonstrated that DCA plan evaluation parameters can be ameliorated by using the DMD method. This new method improves DCA plan quality and reaches similar results with VMAT in terms of dosimetric parameters. We believe that DCA-DMD is a simple and effective technique for SBRT and can be preferred due to shorter treatment and planning time.
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http://dx.doi.org/10.1002/acm2.12237DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5768002PMC
January 2018

In Regard to Kim et al.

Int J Radiat Oncol Biol Phys 2017 12;99(5):1306-1307

Department of Radiation Oncology, Acibadem University School of Medicine, Maslak, Istanbul, Turkey.

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http://dx.doi.org/10.1016/j.ijrobp.2017.08.034DOI Listing
December 2017

International guideline for the delineation of the clinical target volumes (CTV) for nasopharyngeal carcinoma.

Radiother Oncol 2018 01 15;126(1):25-36. Epub 2017 Nov 15.

Division of Radiation Oncology, National Cancer Centre Singapore, Duke-NUS Medical School, Singapore. Electronic address:

Purpose: Target delineation in nasopharyngeal carcinoma (NPC) often proves challenging because of the notoriously narrow therapeutic margin. High doses are needed to achieve optimal levels of tumour control, and dosimetric inadequacy remains one of the most important independent factors affecting treatment outcome.

Method: A review of the available literature addressing the natural behaviour of NPC and correlation between clinical and pathological aspects of the disease was conducted. Existing international guidelines as well as published protocols specified by clinical trials on contouring of clinical target volumes (CTV) were compared. This information was then summarized into a preliminary draft guideline which was then circulated to international experts in the field for exchange of opinions and subsequent voting on areas with the greatest controversies.

Results: Common areas of uncertainty and variation in practices among experts experienced in radiation therapy for NPC were elucidated. Iterative revisions were made based on extensive discussion and final voting on controversial areas by the expert panel, to formulate the recommendations on contouring of CTV based on optimal geometric expansion and anatomical editing for those structures with substantial risk of microscopic infiltration.

Conclusion: Through this comprehensive review of available evidence and best practices at major institutions, as well as interactive exchange of vast experience by international experts, this set of consensus guidelines has been developed to provide a practical reference for appropriate contouring to ensure optimal target coverage. However, the final decision on the treatment volumes should be based on full consideration of individual patients' factors and facilities of an individual centre (including the quality of imaging methods and the precision of treatment delivery).
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http://dx.doi.org/10.1016/j.radonc.2017.10.032DOI Listing
January 2018

Robotic radiosurgery of head and neck paragangliomas: a single institution experience.

Asia Pac J Clin Oncol 2018 Apr 24;14(2):e3-e7. Epub 2017 May 24.

Department of Radiation Oncology, Acibadem University, Istanbul, Turkey.

Aim: CyberKnife is a robotic stereotactic radiotherapy system. The aim of this study is to evaluate the effectiveness and the safety of CyberKnife on treating head and neck paragangliomas and to report our results.

Methods: Between March 2009 and June 2014, 12 patients with head and neck paragangliomas have been referred to our clinic: in three cases had jugular paragangliomas, five cases had carotid body paragangliomas and three cases had tympanic paragangliomas. One patient had bilateral neck paragangliomas (right neck; carotid body paraganglioma, left neck; jugular pargangliomas). All of them received fractionated stereotactic radiotherapy with CyberKnife up to a total median dose of 24 Gy (reference isodose 67-90%). The median tumor volume was 35.5 cc (range, 5.3-113.8 cc). The median follow up was 30 months (range, 0-66 months). Local tumor control was assessed according to RECIST criteria on follow-up imaging studies.

Results: There were no acute or late toxicity related with stereotactic radiotherapy after treatment. No local tumor progression was observed on magnetic resonance imaging and none of our patients showed progressive clinical status. Seven tumors shrinked in size (54%). Five tumors (46%) had stable size during follow up. Local control rate was 100%.

Conclusion: Stereotactic radiotherapy is a good alternative to surgery for the treatment of head and neck paragangliomas coming up with a clear benefit of acute and late side effects. CyberKnife seems to be a safe and efficient system treating head and neck paragangliomas.
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http://dx.doi.org/10.1111/ajco.12695DOI Listing
April 2018