Genitourinary Cancer

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SU_20_2204 - Effectiveness of Adjuvant Radiation Therapy After Radical Cystectomy for Locally Advanced Bladder Cancer

Sunday, October 21
1:15 PM - 2:45 PM
Location: Innovation Hub, Exhibit Hall 3

Effectiveness of Adjuvant Radiation Therapy After Radical Cystectomy for Locally Advanced Bladder Cancer
B. W. Fischer-Valuck1, J. M. Michalski1, J. P. Christodouleas2, E. Kim3, T. A. DeWees1, G. L. Andriole4, V. Arora5, A. Bullock4, R. Carmona2, R. Figenshau3, R. Grubb3, T. J. Guzzo6, E. Knoche5, S. B. Malkowicz6, R. Mamtani7, R. Pachynski5, J. Picus5, B. Roth5, H. A. Gay1, and B. C. Baumann1; 1Washington University School of Medicine, Department of Radiation Oncology, St. Louis, MO, 2University of Pennsylvania, Department of Radiation Oncology, Philadelphia, PA, 3Washington University School of Medicine, Department of Urology, St. Louis, MO, 4Division of Urological Surgery, Washington University School of Medicine, St. Louis, MO, 5Washington University School of Medicine, Department of Medical Oncology, St. Louis, MO, 6University of Pennsylvania, Department of Urology, Philadelphia, PA, 7University of Pennsylvania, Department of Medical Oncology, Philadelphia, PA

Purpose/Objective(s): Local-regional failure (LF) for locally advanced bladder cancer (LABC) after radical cystectomy (RC) is common even with chemotherapy (CT) and is associated with high morbidity/mortality. Adjuvant radiotherapy (adjRT) can reduce LF and may enhance overall survival (OS) but has no defined role. We hypothesized that the addition of adjRT would improve OS in LABC in a large multi-institutional cohort.

Materials/Methods: We identified ≥pT3 pN0-3, M0 LABC pts in the National Cancer Database diagnosed in 2004 – 2013 who underwent RC +/- adjRT and who met the NRG-GU001 adjRT trial selection criteria based on surgical/pathologic features. AdjRT cohort included pts treated to ≥40Gy to the pelvis within 1 year of diagnosis. Patients who died within 30 days of surgery were excluded. Propensity matching (1:3) was performed to match RC pts who received adjRT vs. those who did not. OS was calculated using Kaplan-Meier. Factors significant on univariate analysis were entered into Cox proportional hazards regression model to identify predictors of OS.

Results: 15,124 RC pts were identified, with 499 (3.3%) receiving adjRT. Median OS was 20.8 months (95% CI, 20.3-21.3) for RC versus 20.0 months (95% CI, 18.2-21.8) for adjRT [P=0.18]. On multivariable analysis (MVA), adjRT was associated with improved OS [HR: 0.86 (95% CI, 0.78-0.96); P=0.008]. Other factors in MVA associated with improved OS included: private insurance [HR 0.91 (95% CI, 0.87-0.96); P<0.0001], adenocarcinoma histology [HR 0.82 (95% CI, 0.71-0.94); P=0.005], increasing number of nodes examined [HR 0.99 (95% CI, 0.98-0.99); P<0.0001], single-agent chemotherapy [HR 0.82 (95% CI, 0.74-0.91); P<0.0001] and multi-agent chemotherapy [HR 0.69 (95% CI, 0.66-0.72); P<0.0001]. Factors associated with worse OS were: positive margins, squamous histology, and increasing age, Charlson-Deyo comorbidity score, pT stage, & pN stage (all P<0.01). On MVA of subgroups, adjRT was associated with significantly improved OS in pts with urothelial carcinoma [HR 0.88 (95% CI, 0.78-0.99); P=0.044], positive margins [HR 0.70 (95%CI 0.60 -0.82); p<0.0001)], pN+ [HR 0.78 (95% CI, 0.67-0.90); p=0.001], & pT4 disease [HR 0.80 (95% CI, 0.69-0.92); P=0.002]. For urothelial pts, MVA demonstrated an OS benefit for adjRT for positive margins [HR: 0.75 (95% CI, 0.63-0.90); p=0.002], pN+ [HR 0.80 (95% CI, 0.67-0.94); P=0.007], & pT4 [HR 0.79 (95% CI, 0.67-0.93); P=0.005]. Propensity score matching on demographic, clinical, & treatment variables yielded 1858 pts (474 with adjRT). In the matched cohort, adjRT was associated with improved OS on MVA [HR 0.85 (95% CI, 0.75-0.96); P=0.009] with median OS of 16.9 months [95% CI, 15.6 – 18.1] for RC vs. 19.8 months [95% CI, 18.0 – 21.6] for adjRT (P=0.045).

Conclusion: In this observational study, adjRT was associated with improved OS in LABC. While the data is retrospective, the results lend support to the use of adjRT in selected pts with LABC, regardless of histology. Prospective trials of adjRT are warranted.

Author Disclosure: B.W. Fischer-Valuck: None. J.M. Michalski: Independent Contractor; Sheila Michalski and Associates. Research Grant; NCI. https://medicine.wustl.edu/news/effort-improve-radiation-therapy-veterans-receives-nearly-4-million/; Veteran's Administration. Consultant; Veteran's Administration. Stock; ViewRay Inc. Chair Radiation Oncology Committee; NRG Oncology. Radiation Oncology Practice Assessment; Veterans Affairs. Co-chair GU Steering Committee; NCI. E. Kim: None. T.A. DeWees: None. G.L. Andriole: Consultant; Amgen, Augmenix, GlaxoSmithKline, Janssen Biotech, Inc, Myriad Genetics, Steba Biotech, Bayer. V. Arora: None. A. Bullock: None. R. Figenshau: None. E. Knoche: None. B. Roth: None.

Benjamin Fischer-Valuck, MD

Washington University in St. Louis

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