Publications by authors named "Melek Tugce Yilmaz"

16 Publications

  • Page 1 of 1

In Regard to Helm et al.

Int J Radiat Oncol Biol Phys 2021 Apr;109(5):1658

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

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http://dx.doi.org/10.1016/j.ijrobp.2020.12.017DOI Listing
April 2021

Adjuvant vaginal cuff brachytherapy: dosimetric comparison of conventional versus 3-dimensional planning in endometrial cancer.

J Contemp Brachytherapy 2020 Dec 16;12(6):601-605. Epub 2020 Dec 16.

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

Purpose: To evaluate dosimetric differences between point-based 2-dimensional (2D) vaginal brachytherapy (VBT) treatment planning technique and volume-based 3-dimensional (3D) VBT method for endometrial cancer (EC).

Material And Methods: Ten patients with uterine-confined EC treated with VBT were included in this study. All patients received 27.5 Gy in 5 fractions. Three different treatment plans were performed for each patient: plan A for dose prescribed to the entire vaginal wall thickness delineated via computed tomography guidance, plan B for dose prescribed to the vaginal mucosa/cylinder surface, and plan C for dose prescribed to 5 mm beyond the vaginal mucosa/cylinder surface. Dose-volume histograms (DVH) of treatment volumes and organs at risk (OARs) were evaluated and compared.

Results: DVH analysis of target volume doses (D, D, and D) showed a significant difference between plan A and plan B ( = 0.005), and plan B was found lower. D for plan C was significantly higher than plan A ( = 0.009), but for D and D, no statistically significant difference was found ( = 0.028 and = 0.028, respectively). In terms of OARs doses, including vagina, rectum, bladder, and sigmoid, D doses were significantly higher in plan A than plan B ( = 0.009, = 0.009, = 0.005, and = 0.005, respectively). All these doses were also significantly lower than in plan C ( = 0.005, = 0.012, and = 0.013, respectively), except for sigmoid ( = 0.155).

Conclusions: In this dosimetric analysis, we have shown that the volume-based 3D VBT technique provides the ability to balance the target dose against the sparing of OARs. Therefore, in the new modern 3D treatment era, instead of normalization of the dose to standard reference points, customized 3D volume-based VBT planning should be recommended.
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http://dx.doi.org/10.5114/jcb.2020.101694DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7787204PMC
December 2020

A hesitated approach: primary radiotherapy for keloids-a case series.

Strahlenther Onkol 2021 Jan 4. Epub 2021 Jan 4.

Department of Radiation Oncology, Hacettepe University Medical School, 06100, Ankara, Turkey.

Purpose: To assess the efficacy and toxicity of hypofractionated radiotherapy (RT) alone in treatment-resistant symptomatic keloids.

Methods: Six patients with a total of 13 inoperable large keloid lesions and no response to previous treatments were admitted to our department between 2017 and 2019. All patients were examined for detailed wound localization, size, contour, and color assessment, and for objective and subjective symptoms. Response to treatment was graded as "complete remission" in case of full symptomatic relief and >75% decrease in lesion size, as "partial remission" in case of partial symptomatic relief and 25-75% decrease in lesion size, and as "stable disease" in case of no symptomatic relief or <25% decrease in lesion size. Patients were followed up monthly for the first 3 months and every 3 months thereafter by physical examination.

Results: A total dose of 37.5 Gy external RT in five fractions was prescribed by 6‑MeV electrons in 4 patients and 6‑MV photons in 2 patients. Complete response was obtained in all patients at the 6‑month control. All patients were satisfied with cosmetic results at their last control. Grade 2 dermatitis developed in all patients during the second week of RT but resolved completely in all after 6 months following the end of RT.

Conclusion: In keloids that are unresponsive to standard treatment, hypofractionated RT using a total dose of 37.5 Gy in five fractions is feasible.
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http://dx.doi.org/10.1007/s00066-020-01736-3DOI Listing
January 2021

Parotid gland stem cells: Mini yet mighty.

Head Neck 2021 Apr 27;43(4):1122-1127. Epub 2020 Nov 27.

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

Background: Our aim was to evaluate the correlation between the radiation doses to parotid gland (PG) stem cells and xerostomia.

Methods: Patients diagnosed with head and neck cancer (HNC) were retrospectively evaluated, and xerostomia inventory (XI) was applied to these patients. PG stem cells were delineated on the treatment planning CT, and the mean doses to the PG stem cells calculated.

Results: The total test score and mean doses to bilateral PGs were significantly correlated (r = .34, P = .001), and the mean doses to bilateral PG stem cell niches were significantly correlated with the total test score (r = .32, P = .002).

Conclusions: In this study, we found that the mean dose to PG stem cells can predict dry mouth as much as the mean dose to the PG.
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http://dx.doi.org/10.1002/hed.26556DOI Listing
April 2021

Stereotactic body radiotherapy in patients with early-stage non-small cell lung cancer: Does beam-on time matter?

Jpn J Clin Oncol 2020 Sep;50(10):1182-1187

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

Purpose: Stereotactic body radiotherapy (SBRT) is an effective treatment option for patients with early-stage non-small cell lung cancer (NSCLC). In this study, we evaluated the treatment results using two different SBRT techniques and the effect of beam-on time (BOT) on treatment outcomes.

Methods: Between July 2007 and January 2018, 142 patients underwent SBRT for primary NSCLC. We have delivered SBRT using either respiratory tracking system (RTS) or internal-target-volume (ITV)-based motion management techniques. The effect of age, tumor size, pretreatment tumor SUVmax value, presence of tissue diagnosis, histopathological subtype, operability status, tumor location, motion management technique, BED10 value, BOT on overall survival (OS), loco-regional control (LRC), event-free survival (EFS) and primary tumor control (PTC) were evaluated.

Results: Median age of the patients was 70 years (range, 39-91 years). Most of the patients were inoperable (90%) at the time of SBRT. Median BED10 value was 112.5 Gy. With a median follow-up of 25 months, PTC was achieved in 91.5% of the patients. Two-year estimated OS, LRC, PTC and EFS rates were 68, 63, 63 and 53%, respectively. For the entire group, OS was associated with BOT (P = 0.027), and EFS was associated with BOT (P = 0.027) and tumor size (P = 0.015). For RTS group, OS was associated with age (P = 0.016), EFS with BOT (P = 0.05) and tumor size (P = 0.024), LRC with BOT (P = 0.008) and PTC with BOT (P = 0.028). The treatment was well tolerated in general.

Conclusion: SBRT is an effective and safe treatment with high OS, LRC, EFS and PTC rates in patients with primary NSCLC. Protracted BOT might deteriorate SBRT outcomes.
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http://dx.doi.org/10.1093/jjco/hyaa093DOI Listing
September 2020

Stereotactic radiotherapy in patients with oligometastatic or oligoprogressive gynecological malignancies: a multi-institutional analysis.

Int J Gynecol Cancer 2020 06 8;30(6):865-872. Epub 2020 Apr 8.

Department of Radiation Oncology, Hacettepe Universitesi Tip Fakultesi, Ankara, Turkey.

Introduction: Data supporting stereotactic body radiotherapy for oligometastatic patients are increasing; however, the outcomes for gynecological cancer patients have yet to be fully explored. Our aim is to analyze the clinical outcomes of stereotactic body radiotherapy in the treatment of patients with recurrent or oligometastatic ovarian cancer or cervical cancer.

Methods: The clinical data of 29 patients (35 lesions) with oligometastatic cervical cancer (21 patients, 72%) and ovarian carcinoma (8 patients, 28%) who were treated with stereotactic body radiotherapy for metastatic sites were retrospectively evaluated. All patients had <5 metastases at diagnosis or during progression, and were treated with stereotactic body radiotherapy for oligometastatic disease. Patients with ≥5 metastases or with brain metastases and those who underwent re-irradiation for primary site were excluded. Age, progression time, mean biologically effective dose, and treatment response were compared for overall survival and progression-free survival.

Results: A total of 29 patients were included in the study. De novo oligometastatic disease was observed in 7 patients (24%), and 22 patients (76%) had oligoprogression. The median follow-up was 15.3 months (range 1.9-95.2). The 1 and 2 year overall survival rates were 85% and 62%, respectively, and the 1 and 2 year progression-free survival rates were 27% and 18%, respectively. The 1 and 2 year local control rates for all patients were 84% and 84%, respectively. All disease progressions were observed at a median time of 7.7 months (range 1.0-16.0) after the completion of stereotactic body radiotherapy. Patients with a complete response after stereotactic body radiotherapy for oligometastasis had a significantly higher 2 year overall survival and progression-free survival compared with their counterparts. In multivariate analysis, early progression (≤12 months) and complete response after stereotactic body radiotherapy for oligometastasis were the significant prognostic factors for improved overall survival. However, no significant factor was found for progression-free survival in the multivariable analysis. No patients experienced grade 3 or higher acute or late toxicities.

Conclusions: Patients with early detection of oligometastasis (≤12 months) and with complete response observed at the stereotactic body radiotherapy site had a better survival compared with their counterparts. Stereotactic body radiotherapy at the oligometastatic site resulted in excellent local control rates with minimal toxicity, and can potentially contribute to long-term survival.
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http://dx.doi.org/10.1136/ijgc-2019-001115DOI Listing
June 2020

Stereotactic ablative radiotherapy for bone metastasis of gastrointestinal stromal tumor: Case report and review of the literature.

Rep Pract Oncol Radiother 2020 May-Jun;25(3):331-335. Epub 2020 Feb 24.

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

Background: Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors of the gastrointestinal tract. These tumors are rare and only make bone metastases at a rate of 5%.

Case Summary: A 31-year-old male with a GIST presented with solitary bone metastasis at the right iliac bone. We performed stereotactic ablative radiotherapy (SABR) and achieved excellent local control. Herein, our case is presented, and a short review of the literature is carried out.

Conclusion: SABR should be considered as a treatment option in GIST with bone metastasis.
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http://dx.doi.org/10.1016/j.rpor.2020.02.013DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7114605PMC
February 2020

Dosimetric comparison of two different applicators and rectal retraction methods used in inverse optimization-based intracavitary brachytherapy for cervical cancer.

J Contemp Brachytherapy 2020 Feb 28;12(1):35-43. Epub 2020 Feb 28.

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

Purpose: The purpose of this study was to evaluate the dosimetric differences between two different applicators and rectal-retraction methods used in image-guided brachytherapy (IGBT) for locally advanced cervical cancer (LACC).

Material And Methods: Ten patients with LACC treated with definitive chemoradiotherapy and inverse optimization-based IGBT were included in this study. In each patient, at least one fraction of IGBT was performed using tandem-ovoids (TO) with vaginal gauze packing (VGP) or tandem-ring (TR) with rectal-retractor (RR). High-risk clinical target volume (CTV) and intermediate-risk CTV (CTV) were defined as CTVs, and bladder, rectum, sigmoid, small bowel, urethra, and vaginal mucosa were defined as organs at risk (OARs). All patients received 50.4 Gy external beam radiotherapy (EBRT) in 28 fractions. After EBRT, 28 Gy high-dose-rate (HDR) IGBT in 4 fractions was delivered to central disease. A plan comparison was performed using dose-volume histogram (DVH) and treatment planning parameters for CTVs and OARs.

Results: There were no significant differences in D values of CTV. In terms of rectum dose, TR with RR was found to be significantly better than TO with VGP ( < 0.0001 for D and < 0.013 for V). Although, there were no statistically significant differences in D value of bladder, sigmoid, small bowel, upper vaginal mucosa, and urethra, mean value of D for all defined OARs were found lower in TR than in TO. Bladder V, upper vaginal mucosa V, middle and lower vaginal mucosa D values were all found to be significantly lower for TR than for TO ( < 0.035). CTV and CTV volumes contoured in TR were approximately 11% and 9% smaller than TO, respectively.

Conclusions: The results showed that there were no statistically differences in D value of CTV and CTV. However, all DVH parameters for OARs in TR with RR were found to be better than in TO with VGP.
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http://dx.doi.org/10.5114/jcb.2020.92699DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7073337PMC
February 2020

FLASH-radiotherapy: A new perspective in immunotherapy era?

Radiother Oncol 2020 04 19;145:137. Epub 2020 Jan 19.

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

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http://dx.doi.org/10.1016/j.radonc.2019.12.015DOI Listing
April 2020

Comments on "Risk factors for vertebral compression fracture after spine stereotactic body radiation therapy: Long-term results of a prospective phase 2 study".

Radiother Oncol 2020 04 18;145:127. Epub 2020 Jan 18.

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

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http://dx.doi.org/10.1016/j.radonc.2019.12.014DOI Listing
April 2020

Comments on "Prognostic factors for survival in patients with metastatic malign melanoma treated with ipilimumab: Turkish Oncology Group study".

J Oncol Pharm Pract 2019 12 21;25(8):2060-2062. Epub 2019 Jun 21.

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

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http://dx.doi.org/10.1177/1078155219858177DOI Listing
December 2019

In Regard to Videtic et al.

Int J Radiat Oncol Biol Phys 2019 06;104(2):466-467

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

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http://dx.doi.org/10.1016/j.ijrobp.2019.02.012DOI Listing
June 2019

Abscopal Effect, From Myth to Reality: From Radiation Oncologists' Perspective.

Cureus 2019 Jan 9;11(1):e3860. Epub 2019 Jan 9.

Radiation Oncology, Hacettepe University Medical School, Ankara, TUR.

The abscopal effect is mediated by a systemic anti-tumor immune response and reflects the regression of non-irradiated metastatic lesions at a distance from the primary site of irradiation. This review will focus on understanding the biological rationale behind the abscopal effect of radiotherapy (RT), which has a recently renewed interest as a result of the successes achieved with immunotherapy and RT in combination. Both RT and immunotherapy are standard components of modern treatment regimens. Combination of these two modalities results in an increased response in the irradiated lesions themselves and the metastatic regions distant from the site of irradiation. We will summarize the abscopal effect of radiotherapy, in particular, the synergistic effect of RT and immunotherapy.
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http://dx.doi.org/10.7759/cureus.3860DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6414182PMC
January 2019

The Synergistic Effect of Immune Checkpoint Blockade and Radiotherapy in Recurrent/Metastatic Sinonasal Cancer.

Cureus 2018 Oct 29;10(10):e3519. Epub 2018 Oct 29.

Radiation Oncology, Hacettepe University Medical School, Ankara, TUR.

Treatment options for recurrent/metastatic sinonasal cancer (RMSNC) patients are limited. We present two cases with RMSNC treated with a combination of immune checkpoint blockade and hypo-fractionated stereotactic radiotherapy (HSRT).  Case 1 presented with RMSNC three months after the primary treatment. The patient progressed under first-line chemotherapy and pembrolizumab was offered. The disease progressed after the sixth cycle. We performed reirradiation with HSRT to the primary site. Case 2 presented with local recurrence eight years after the primary treatment for maxillary sinus cancer. He refused surgery and chemotherapy and was offered nivolumab treatment. After two doses, we performed reirradiation with HSRT. Case 1 showed regression at both the local and the metastatic sites after radiotherapy. The second patient's symptoms resolved completely three months after radiotherapy. The HSRT and immune checkpoint blockade combination is a promising treatment option for patients with RMSNC.
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http://dx.doi.org/10.7759/cureus.3519DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6318133PMC
October 2018

Comments on "High lymphocyte count during neoadjuvant chemoradiotherapy is associated with improved pathologic complete response in esophageal cancer".

Radiother Oncol 2019 02 17;131:239. Epub 2018 Oct 17.

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

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http://dx.doi.org/10.1016/j.radonc.2018.10.001DOI Listing
February 2019

In Regard to Chen et al.

Int J Radiat Oncol Biol Phys 2018 07 20;101(4):998. Epub 2018 Jun 20.

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

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http://dx.doi.org/10.1016/j.ijrobp.2018.04.079DOI Listing
July 2018