Publications by authors named "Sam S Chang"

398 Publications

Urological Oncology: Bladder, Penis and Urethral Cancer, and Basic Principles of Oncology.

Authors:
Sam S Chang

J Urol 2021 Nov 16:101097JU0000000000002313. Epub 2021 Nov 16.

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http://dx.doi.org/10.1097/JU.0000000000002313DOI Listing
November 2021

Urological Oncology: Bladder, Penis and Urethra Cancer, and Basic Principles of Oncology.

Authors:
Sam S Chang

J Urol 2021 Oct 18:101097JU0000000000002268. Epub 2021 Oct 18.

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http://dx.doi.org/10.1097/JU.0000000000002268DOI Listing
October 2021

Association Between Surgical Volume and Survival Among Patients With Variant Histologies of Bladder Cancer.

Urology 2021 Oct 1. Epub 2021 Oct 1.

Department of Surgery & Perioperative Care, Dell Medical School at the University of Texas at Austin, Austin, TX. Electronic address:

Objective: To examine the relationship between hospital volume and the management of bladder cancer variant histology. Variant histologies of bladder cancer are rare which limits the ability for providers to develop expertise however there is a clear hospital and/or surgeon-volume relationship for management of rare or complex surgical and/or medical diseases.

Methods: We queried the National Cancer Database from 2004-2016 for all cases of bladder cancer, identifying cases of variant histology. Our primary outcome was overall survival while secondary outcomes included identifying treatment patterns. Hospitals were stratified into those that managed ≤2, >2-4, >4-6, and ≥6 cases per year of variant histology.

Results: We identified 23,284 patients with bladder cancer of variant histology who were treated at 1301 hospitals. Few institutions had high volume experience with this disease: 18.5% (n = 241) treated >2 patients annually and 5.7% (n = 76) treated >4 cases annually. Hospital volume positively correlated with utilization of early radical cystectomy (RC) in non-muscle invasive disease and neoadjuvant chemotherapy in muscle-invasive disease. On multivariable analysis, increased hospital volume was associated with improved survival. After stratifying by sub-type, hospital volume continued to be associated with improved survival for squamous, small cell, and sarcomatoid cancers.

Conclusion: Management of variant histology urothelial carcinoma at high-volume centers is associated with improved overall survival. The mechanisms of this are multifactorial, and future research should focus on improvement opportunities for low-volume hospitals, centralization of care, and/or increased access to care at high-volume centers.
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http://dx.doi.org/10.1016/j.urology.2021.09.009DOI Listing
October 2021

Urological Oncology: Bladder, Penis and Urethral Cancer, and Basic Principles Of Oncology.

Authors:
Sam S Chang

J Urol 2021 Dec 8;206(6):1517-1519. Epub 2021 Sep 8.

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http://dx.doi.org/10.1097/JU.0000000000002213DOI Listing
December 2021

Urological Oncology: Bladder, Penis and Urethral Cancer, and Basic Principles OF Oncology.

Authors:
Sam S Chang

J Urol 2021 Nov 16;206(5):1326-1328. Epub 2021 Aug 16.

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http://dx.doi.org/10.1097/JU.0000000000002156DOI Listing
November 2021

Urological Oncology: Bladder, Penis and Urethral Cancer, and Basic Principles of Oncology.

Authors:
Sam S Chang

J Urol 2021 Oct 23;206(4):1061-1062. Epub 2021 Jul 23.

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http://dx.doi.org/10.1097/JU.0000000000001957DOI Listing
October 2021

Urological Oncology: Bladder, Penis and Urethral Cancer, and Basic Principles of Oncology.

Authors:
Sam S Chang

J Urol 2021 Sep 16;206(3):769-772. Epub 2021 Jun 16.

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http://dx.doi.org/10.1097/JU.0000000000001908DOI Listing
September 2021

Differential effect of body mass index by gender on oncological outcomes in patients with renal cell carcinoma.

J Cancer Res Ther 2021 Apr-Jun;17(2):420-425

Department of Urologic Surgery, Vanderbilt University Medical Center, Nashville, TN, USA.

Objectives: To investigate the relationship between gender, body mass index (BMI), and prognosis in renal cell carcinoma (RCC) patients.

Materials And Methods: We retrospectively reviewed 1353 patients with RCC who underwent a partial or radical nephrectomy between 1988 and 2015. The association among sex, BMI, stage, grade, overall survival (OS), and recurrence-free survival (RFS) was analyzed.

Results: The median age of the patients was 59.4 ± 11.9 years. Female patients had proportionally lower grade tumors than male patients (Grade I-II in 75.5% vs. 69.3% in women and men, respectively, P = 0.022). There was no relationship between Fuhrman grade and BMI when substratified by gender (p > 0.05). There was a nonsignificant trend toward more localized disease in female patients (p = 0.058). There was no relationship between T stage and BMI when stratified by gender (p > 0.05). Patients with higher BMI had significantly better OS (p = 0.0004 and P = 0.0003) and RFS (P = 0.0209 and P =0.0082) whether broken out by lower 33 or 25 percentile. Male patients with higher BMI had significantly better OS and RFS rates. However, there was no relationship between BMI and OS or RFS for female patients (P > 0.05). Multivariate analysis of the entire cohort demonstrated that a BMI in the lower quartile independently predicts OS (hazard ratio 1.604 [95% confidence interval: 1.07-2.408], P = 0.022) but not RFS (P > 0.05). When stratified by gender, there was no relationship between BMI and either OS or RFS (P > 0.05).

Conclusions: Increasing BMI was associated with RCC prognosis. However, the clinical association between BMI and oncologic outcomes may be different between men and women.
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http://dx.doi.org/10.4103/jcrt.JCRT_546_18DOI Listing
June 2021

Renal Mass and Localized Renal Cancer: Evaluation, Management, and Follow-Up: AUA Guideline: Part I.

J Urol 2021 Aug 11;206(2):199-208. Epub 2021 Jul 11.

Fox Chase Cancer Center, Philadelphia, Pennsylvania.

Purpose: This AUA Guideline focuses on evaluation/counseling/management of adult patients with clinically-localized renal masses suspicious for cancer, including solid-enhancing tumors and Bosniak 3/4 complex-cystic lesions.

Materials/methods: The Renal Mass and Localized Renal Cancer guideline underwent an update literature review which resulted in the 2021 amendment. When sufficient evidence existed, the body of evidence was assigned a strength rating of A (high), B (moderate), or C (low) for support of Strong, Moderate, or Conditional Recommendations. In the absence of sufficient evidence, additional information is provided as Clinical Principles and Expert Opinions (table 1[Table: see text]).

Results: Great progress has been made regarding the evaluation/management of clinically-localized renal masses. These guidelines provide updated, evidence-based recommendations regarding evaluation/counseling including the evolving role of renal-mass-biopsy (RMB). Given great variability of clinical/oncologic/functional characteristics, index patients are not utilized and the panel advocates individualized counseling/management. Options for intervention (partial-nephrectomy (PN), radical-nephrectomy (RN), and thermal-ablation (TA)) are reviewed including recent data about comparative-effectiveness/potential morbidities. Oncologic issues are prioritized while recognizing the importance of functional-outcomes for survivorship. Granular criteria for RN are provided to help reduce overutilization of RN while also avoiding imprudent PN. Priority for PN is recommended for clinical T1a lesions, along with selective utilization of TA, which has good efficacy for tumors≤3.0 cm. Recommendations for genetic-counseling have been revised and considerations for adjuvant-therapies are addressed. Active-surveillance and follow-up after intervention are discussed in an adjunctive article.

Conclusion: Several factors require consideration during counseling/management of patients with clinically-localized renal masses including general health/comorbidities, oncologic-considerations, functional-consequences, and relative efficacy/potential morbidities of various management-strategies.
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http://dx.doi.org/10.1097/JU.0000000000001911DOI Listing
August 2021

Renal Mass and Localized Renal Cancer: Evaluation, Management, and Follow-up: AUA Guideline: Part II.

J Urol 2021 Aug 11;206(2):209-218. Epub 2021 Jul 11.

Consultant Methodologist, Ontario, Canada.

Purpose: This AUA Guideline focuses on active surveillance (AS) and follow-up after intervention for adult patients with clinically-localized renal masses suspicious for cancer, including solid enhancing tumors and Bosniak 3/4 complex cystic lesions.

Materials And Methods: In January 2021, the Renal Mass and Localized Renal Cancer guideline underwent additional amendment based on a current literature-search. This literature search retrieved additional studies published between July 2016 to October 2020 using the same Key Questions and search criteria from the Renal Mass and Localized Renal Cancer guideline. When sufficient evidence existed, the body of evidence was assigned strength-rating of A (high), B (moderate), or C (low) for support of Strong, Moderate, or Conditional Recommendations. In the absence of sufficient evidence, additional information is provided as Clinical Principles and Expert Opinions (table 1[Table: see text]).

Results: AS with potential delayed intervention should be considered for patients with solid, enhancing renal masses <2cm or Bosniak 3-4 lesions that are predominantly-cystic. Shared decision-making about AS should consider risks of intervention/competing mortality versus the potential oncologic benefits of intervention. Recommendations for renal mass biopsy and considerations for periodic clinical/imaging-based surveillance are discussed. After intervention, risk-based surveillance protocols are defined incorporating clinical/laboratory evaluation and abdominal/chest imaging designed to detect local/systemic recurrences and possible treatment-related sequelae, such as progressive renal-insufficiency.

Conclusion: AS is a potential management strategy for some patients with clinically-localized renal masses that requires careful risk-assessment, shared decision-making and periodic-reassessment. Follow-up after intervention is designed to identify local/systemic recurrences and potential treatment-related sequelae. A risk-based approach should be prioritized with selective use of laboratory/imaging resources.
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http://dx.doi.org/10.1097/JU.0000000000001912DOI Listing
August 2021

The prevention of extraction site incisional hernia after robotic-assisted radical prostatectomy.

J Robot Surg 2021 Apr 2;15(2):315-317. Epub 2021 Feb 2.

Department of Urologic Surgery, Vanderbilt University Medical Center, 1211 Medical Center Drive, Nashville, TN, USA.

Extraction site incisional hernia (IH) has been recognized as an important complication in minimally invasive procedures but has not been as well characterized following robotic-assisted laparoscopic prostatectomy (RALP). Approximately 29% of IH required surgical repair. A number of techniques have been utilized to reduce the rates of IH following minimally invasive procedures. First, off-midline extraction was investigated, this did not demonstrate a reduction in incisional hernia rates. Recently, supra-umbilical transverse incisions have been utilized to extract prostate specimen and this method decreased the extraction site IH rate compared to the vertical midline incision. In addition, the choice of fascial closure technique and choice of the suture may influence the incidence of extraction site IH. For example, studies showed that abdominal fascial closure using a nonabsorbable suture and a continuous running suture technique decreased IH rate from 32 to 17%. Finally, "the small bites technique" has been recommended to reduce hernia incidence after midline fascial closure following a randomized controlled trial (RCT) which demonstrated the superiority of the small-bite technique. In summary, a supra-umbilical transverse incision to extract the specimen was shown to decrease the rate of extraction site IH. In vertical midline incisional closure, the small bites technique with slowly- or non-absorbable suture, such as #0 or 2-0 PDS II with SH or CT-2 needle (26 mm arch length), reduces the IH rate. Urologists should consider this data to reduce the risk of IH following RALP.
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http://dx.doi.org/10.1007/s11701-021-01204-9DOI Listing
April 2021

Intravesical Anti-PD-1 Immune Checkpoint Inhibition Treats Urothelial Bladder Cancer in a Mouse Model.

J Urol 2021 05 24;205(5):1336-1343. Epub 2020 Dec 24.

Department of Urology, Vanderbilt University Medical Center, Nashville, Tennessee.

Purpose: Nonmuscle-invasive bladder cancer is treated by resection within the bladder and bladder instillment with bacillus Calmette-Guérin or chemotherapy. For bacillus Calmette-Guérin-refractory disease, systemic anti-PD-1 (programmed cell death protein 1) immune checkpoint inhibition is a treatment. Our aim is to test whether intravesical instillment with anti-PD-1 inhibitor treats localized bladder cancer as effectively as systemic administration.

Materials And Methods: We investigated an orthotopic mouse model of urothelial bladder cancer using MBT2 cells instilled into the bladders of syngeneic, wild-type C3H mice. Groups of 10 mice received each treatment for comparison of intravesical anti-PD-1, intraperitoneal anti-PD1, and intravesical chemotherapy. The primary outcome was overall survival and secondary outcomes included long-term immunity and toxicity.

Results: Anti-PD-1 administered by bladder instillment (intravesical route) successfully treats localized bladder cancer and has similar overall survival to anti-PD-1 by systemic route. Anti-PD-1 by either route provides a significant survival advantage over control antibody. Anti-PD-1 increases CD8+ cell infiltration in tumors, particularly when administered intravesically. Antibody treatment avoids toxicity observed for intravesical chemotherapy. Mice who cleared their tumors after initial treatment were rechallenged with tumor engraftment 3-9 months later without any additional treatment. Initial anti-PD-1-treated mice did not grow tumors when rechallenged, which suggests long-term immunity exists, but initial mitomycin-treated mice readily grew tumors indicating no immunity occurred by chemotherapy treatment.

Conclusions: Intravesical administration of anti-PD-1 is a promising treatment route for localized bladder cancer, with comparable overall survival to systemic anti-PD-1 in this mouse model. Intravesical anti-PD-1 increases CD8+ T cells in treated tumors and long-term immunity was seen to tumor rechallenge.
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http://dx.doi.org/10.1097/JU.0000000000001576DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8112465PMC
May 2021

Side Effects of Intravesical BCG and Chemotherapy for Bladder Cancer: What They Are and How to Manage Them.

Urology 2021 Mar 10;149:11-20. Epub 2020 Nov 10.

Department of Urology, Vanderbilt University Medical Center, Nashville, TN. Electronic address:

Intravesical therapy for nonmuscle invasive bladder cancer decreases recurrence and progression but carries a high risk of side effects, which limit patient adherence. Appropriate management of the toxicities from intravesical therapy requires consideration of the agent used, the side effects experienced, and the timing of those side effects. Management strategies for intravesical toxicities ideally improve patient tolerance without sacrificing oncologic outcomes. This review aims to provide a comprehensive overview of the available evidence regarding the side effects of intravesical therapies for nonmuscle invasive bladder cancer and to propose practical strategies for toxicity management.
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http://dx.doi.org/10.1016/j.urology.2020.10.039DOI Listing
March 2021

The Impact of Hospital Volume on Short-term and Long-term Outcomes for Patients Undergoing Radical Nephroureterectomy for Upper Tract Urothelial Carcinoma.

Urology 2021 Jan 4;147:135-142. Epub 2020 Sep 4.

Department of Urology, Vanderbilt University Medical Center, Nashville, TN. Electronic address:

Objectives: To examine the effect of hospital volume on short and long-term outcomes for radical nephroureterectomy (RNUx). Upper tract urothelial carcinoma is a rare malignancy that few surgeons have experience with. The hospital volume-outcome relationship has been well established for other cancers but not RNUx.

Methods: The National Cancer Database was queried for all cases of upper tract urothelial carcinoma that underwent RNUx from 2004 to 2016. Average annual hospital volume for radical nephroureterectomy was stratified into tertiles. The upper tertile, defined as 6 or more RNUx per year, was considered high volume while low volume was less than 6 RNUx per year. Kaplan-Meier and Cox proportional hazards regression were used to identify independent predictors of overall survival, and logistic regression was used to identify predictors of perioperative outcomes.

Results: We identified 37,479 RNUx performed across 1290 hospitals. There were no differences in baseline health or cancer staging between patients who presented at low- versus high-volume centers. Both peri-operative survival (30- and 90-day mortality) and long-term overall survival were improved in patients treated at high-volume centers. On multivariable survival analysis, treatment at a high-volume center was associated with improved hazards of survival. This relationship for long-term survival remained consistent on landmark analysis where patients who died within 90 days of surgery were removed.

Conclusions: Treatment at a high-volume hospital was associated not only with improved short-term perioperative outcomes but also with improved overall long-term survival. The mechanism behind this is likely multifactorial with surgeon volume, and ancillary support services all playing critical roles.
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http://dx.doi.org/10.1016/j.urology.2020.07.062DOI Listing
January 2021
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