PV QA 1 - Poster Viewing Q&A 1
Purpose/Objective(s): Adenocarcinoma (AC) accounts for <2% of all primary bladder cancers in the Western world. Treatment for localized AC is extrapolated from urothelial carcinoma (UC) results, with limited data on efficacy in AC, particularly for definitive chemo-radiation (CRT). We hypothesized that overall survival (OS) between AC and UC patients treated with definitive CRT would be equivalent.
Materials/Methods: We queried the NCDB for muscle-invasive (cT2-T4 N0-3 M0) bladder cancer patients diagnosed between 2004-2013 treated with concurrent CRT after TURBT. Patients receiving RT doses < 40 Gy were excluded. OS was analyzed using Kaplan-Meier techniques. Univariate and multivariable (MVA) Cox regression and propensity matching (1:1) were performed for demographic, clinical, and treatment variables. P-values <0.05 were considered significant.
Results: A total of 4,760 patients met inclusion criteria with 74 (1.6%) having AC. Median age (years) was 73 (range: 41-89) for AC and 77 (range: 40-90) for UC. Males accounted for 62% of AC patients and 73% of UC patients. AC had higher ≥cT3 disease compared to UC (p= 0.006) but there was no difference in cN- stage (p= 0.79). Median OS (months) was 25.2 (95% CI 18.5-32.0) for AC versus 24.7 (95% CI 23.6-25.9) for UC (p= 0.453). On MVA, age (HR: 1.02, 95% CI 1.01-1.02; p<0.0001), female sex (HR 1.09, 95% CI 1.02-1.18; p= 0.015), higher Charlson-Deyo comorbidity index (HR 1.30, 95% CI 1.28-1.32; p<0.0001), ≥cT3 disease (HR 1.37, 95% CI 1.21-1.51; p= 0.003), and positive nodal status (HR 1.41, 95% CI 1.32-1.56; p= 0.0001) were associated with worse OS. AC histology was not predictive of OS on MVA (p= 0.313). After propensity matching, 73 patients from each histology group were analyzed (n= 146). Median OS (months) for AC was 25.3 (95% CI 19.4-31.2) versus 18.6 (95% CI 14.7-22.4) for UC (p= 0.630). On subset analysis no co-variables (age, race, sex, cT stage, or cN stage) were associated with improved OS.
Conclusion: To our knowledge, this study is the first to compare outcomes with definitive CRT in patients with adenocarcinoma of the bladder vs. urothelial carcinoma of the bladder. OS favored AC but the differences were not significant. While the data is limited by the small sample size, the results suggest that definitive CRT may be a viable option for patients with AC.
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