Genitourinary Cancer

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SU_24_2244 - Influence of Age on Treatment Outcomes in Intermediate or High-Risk Prostate Cancer Treated With Androgen Deprivation Therapy and Radiation Therapy

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

Influence of Age on Treatment Outcomes in Intermediate or High-Risk Prostate Cancer Treated With Androgen Deprivation Therapy and Radiation Therapy
A. K. Bryant1, K. Kader2, R. Mckay3, J. P. Einck1, J. K. Parsons4, C. J. Kane2, A. J. Mundt Jr1, J. D. Murphy1, and B. S. Rose1; 1Department of Radiation Medicine, University of California, San Diego, La Jolla, CA, 2Department of Urology, University of California, San Diego, La Jolla, CA, 3Department of Hematology-Oncology, University of California, San Diego, La Jolla, CA, 4University of California, San Diego, La Jolla, CA

Purpose/Objective(s): Previous data have suggested that younger patients may have a less robust response to androgen deprivation therapy (ADT) compared to older patients. We investigated the effect of age on immediate prostate-specific antigen (PSA) response and long-term clinical outcomes in a large cohort of US veterans with localized prostate cancer.

Materials/Methods: We identified 6,637 patients with intermediate- (n=2,997) or high-risk (n=3,640) localized prostate cancer diagnosed between 2000-2015 and treated with radiation therapy (RT) and ADT from nationwide Veterans Affairs data. Patients were grouped into 3 age categories (≤ 59, 60-69, and ≥ 70 years old). Immediate treatment response was assessed with 3-month post-RT PSA, grouped into < 0.10 ng/mL, 0.10-0.49 ng/mL, and ≥ 0.50 ng/mL subsets. Long-term outcomes included biochemical recurrence and prostate cancer-specific mortality. The effect of age group on each outcome was assessed with multivariable regression models adjusting for potential confounders. Regression models included ordinal logistic regression for 3-month post-RT PSA, Cox regression for biochemical recurrence, and Fine-Gray competing risks regression for prostate cancer-specific mortality.

Results: 1,103 patients (17%) were ≤ 59 years old at diagnosis, 3,271 (49%) were 60-69 years old, and 2,263 (34%) were ≥ 70 years old. Median follow-up was 6.1 years. Younger patients showed higher 3-month post-RT PSA (7.3% with PSA ≥ 0.50 ng/mL for ≥ 70 years, 11% for 60-69 years, 16% for ≤ 59 years, p<0.001). In regression models, younger age was associated with a greater odds of higher 3-month PSA group (adjusted odds ratio [aOR] 1.85 for ≤ 59 vs. ≥ 70, 95% CI 1.57-2.19; aOR 1.39 for 60-69 vs. ≥ 70, 95% CI 1.22-1.57; p<0.001 for the overall effect of age group). Younger age group was also associated with greater risk of biochemical recurrence (adjusted hazard ratio [aHR] 1.42 for ≤ 59 vs. ≥ 70, 95% CI 1.19-1.70, p<0.001; aHR 1.20 for 60-69 vs. ≥ 70, 95% CI 1.04-1.39, p=0.02) but not prostate cancer-specific mortality (p > 0.05 for all).

Conclusion: In a large nationwide sample of US veterans treated with ADT and RT for localized prostate cancer, younger age was associated with inferior immediate PSA response and higher risk of biochemical recurrence, though we noted no difference in prostate cancer-specific mortality. Additional investigation is needed to determine the reasons for inferior PSA response in younger men with prostate cancer.

Author Disclosure: A.K. Bryant: None. K. Kader: None. R. Mckay: Research Grant; Bayer, Pfizer, Genetech. Advisory Board; Novartis, Janssen. J.P. Einck: Independent Contractor; American College of Radiation Oncology. Board Member; Cure Cervical Cancer. oRG. J.K. Parsons: None. C.J. Kane: Research Grant; SNP Bio. A.J. Mundt: Honoraria; Up to Date, US Oncology, Varian Medical Systems. B.S. Rose: None.

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