3163 - Risk of Death in Octogenarians with Intermediate Risk Prostate Cancer Who Are Treated with Radiation Therapy (RT) Plus Androgen Deprivation Therapy (ADT) Versus Radiation Alone, an NCDB Analysis

T. Dougherty¹, S. B. Hayes², and M. Deng³; ¹Fox Chase Cancer Center, Philadelphia, PA, ²Department of Radiation Oncology, Fox Chase Cancer Center, Philadelphia, PA, ³Department of Biostatistics and Bioinformatics, Fox Chase Cancer Center, Philadelphia, PA

Purpose/Objective(s): Most trials enroll few men over 80 years old. This holds true for the randomized controlled trials that examine the addition of ADT to radiation in men with prostate cancer. Aging is non-linear and men over 80 might uniquely be pre-disposed to ADT related effects, particularly muscle wasting that could increase the risk of falls. Since falls contribute to a non-trivial risk of mortality in the 80+ population, and given ADT’s association with increased risk of falls, we hypothesized that ADT, when added to radiation therapy in octogenarians with intermediate risk prostate cancer, might be associated with worse overall survival. Materials/

Methods: The NCDB was queried for men = 60 years-old who received dose-escalated radiation therapy (>74 Gy) for intermediate risk prostate cancer. Intermediate risk was defined as PSA < 20, Gleason score 7 (either 3+4 or 4+3), and T1 or T2 disease. Men were separated by age and receipt of ADT. Allowable time frame for initiation of ADT was up to 12 months prior to or 2 months after the start of radiation. Overall survival was evaluated using Kaplan-Meier analysis. Cox Proportional hazards were used to determine the relationship between ADT usage on survival in different age cohorts.
Results: There were 10,168 men who received RT + ADT versus 12,396 who received RT alone. In the ADT + RT group, a larger percentage of men had Gleason 4+3 disease (43 % vs 26%, p = 0.01) and a higher PSA (mean 8.6 vs 7.7, p = < 0.001). There were 672 (6.6%) octogenarians who received ADT versus 772 (6.2%) who did not. Hazard ratios for overall survival, accounting for Gleason score, T stage, PSA, and comorbid conditions, are reported for three different age groups (60-69, 70-79, = 80) in the table below:
Conclusion: Consistent with data from randomized controlled trials, younger men (in our example, ages 60-69) have a decreased risk of death when receiving ADT in concert with dose-escalated radiation therapy. Our results show that the overall survival benefit of ADT decreases in older men with intermediate risk prostate cancer, and highlights that octogenarians—a notoriously under-represented group in clinical trials—may benefit the least from the addition of ADT to dose-escalated radiotherapy.

Abstract 3163 – Table 1

Hazard ratios for death in those receiving ADT + RT versus RT alone
Age group	Hazard ratio [95% CI]	p-value
60-69	0.90 [0.81 – 0.99]	0.04
70-79	0.98 [0.90 – 1.06]	0.54
= 80	1.13 [0.97 – 1.32]	0.12