Genitourinary Cancer

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SU_25_2258 - Clinical Outcomes of Radical Prostatectomy Versus Combined External Beam Radiation Therapy and Androgen Deprivation Therapy in Elderly Men With High-Risk Prostate Cancer: A Multi-Institutional Analysis

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

Clinical Outcomes of Radical Prostatectomy Versus Combined External Beam Radiation Therapy and Androgen Deprivation Therapy in Elderly Men With High-Risk Prostate Cancer: A Multi-Institutional Analysis
M. Frager1, N. Cnossen1, and S. M. Shin2; 1Southern California Permanente Medical Group, Los Angeles, CA, 2Southern California Permanente Medical Group, Ontario, CA

Purpose/Objective(s): We evaluated rates of biochemical control, prostate cancer-specific survival, and overall survival in a cohort of elderly men presenting with clinically localized high-risk prostate cancer (HRPCa) definitively treated with radical prostatectomy (RP) or combined external beam radiotherapy (EBRT) and androgen deprivation therapy (ADT) in a multi-center setting.

Materials/Methods: Men aged>70 who were definitively treated from 2008-2016 with either RP or combined EBRT+ADT for HRPCa were included in this study. All clinical data were queried from our IRB-approved tumor registry confirming presence of HRPCa as classified by biopsy gleason score (GS), initial prostate-specific antigen level (iPSA), and clinical tumor stage (T-stage). Survival was calculated from time of surgery or end of EBRT. Differences in baseline characteristics between treatment groups were identified using ANOVA and Chi-Square testing. Clinical predictors of study outcomes were identified through multivariate analysis (MVA). Kaplan-Meier curves were generated for each treatment group and survival differences identified by log rank testing.

Results: 469 men with a median age of 74 were included in this study. Median follow-up of EBRT+ADT and RP patients were 61 and 55 months, respectively. Comparison of baseline characteristics demonstrated that men who underwent EBRT+ADT presented with higher age, iPSA, and T-stage compared to men who underwent RP (Table 1). MVA demonstrated that higher iPSA (HR 1.02, p=.009), GS (HR=1.38, p=.027), and percent positive cores (HR=5.32, p<.001) were associated with inferior biochemical control. Higher iPSA (HR=1.23, p=.04) and GS (HR=3.16, p=.009) were associated with inferior prostate cancer-specific survival. Older age was associated with inferior overall survival (HR=1.06, p=.04). Patients who underwent EBRT+ADT had superior 5-year biochemical control compared to those who underwent RP (65% v. 46%, p<.001). EBRT+ADT patients had inferior overall survival compared to RP patients (79% v. 88%, p=.005), however no difference was seen with respect to prostate cancer-specific survival, (94.2% v. 94.5%, p=.39).

Conclusion: We observed that men treated with combined EBRT+ADT had inferior overall survival compared to men treated with RP—likely an impact of older median age in the EBRT+ADT group. Despite treating disease of higher iPSA and clinical T-stage, combined EBRT+ADT provided superior biochemical control and equivalent prostate cancer-specific survival compared to RP in elderly men with HRPCa. Table 1. Baseline characteristics of patients
RP EBRT+ADT p-value
Patients 103 366 -
Median Age 73 75 <.001
Median iPSA 9.3 12.3 .03
Median (+) Cores 43% 50% .49

T-stage: <2a

43% 45% .04
2a or 2b 51% 40% -
2c 5% 10% -
>2c 1% 5% -

GS: 6

3.9% 5.5% .63
7 13% 13% -
8 53% 46% -
9 or 10 30% 36% -

Author Disclosure: M. Frager: None. N. Cnossen: None.

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SU_25_2258 - Clinical Outcomes of Radical Prostatectomy Versus Combined External Beam Radiation Therapy and Androgen Deprivation Therapy in Elderly Men With High-Risk Prostate Cancer: A Multi-Institutional Analysis



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