Radiotherapy with or without androgen deprivation therapy in intermediate risk prostate cancer?

Androgen deprivation therapy (ADT) is beneficial for unfavorable intermediate-risk (IR) prostate cancer patients receiving curative radiotherapy (RT). However, for favorable IR patients the latest NCCN guidelines recommends RT alone. We retrospectively studied treatment patterns and outcomes of patients with IR prostate cancer in our institution over the past two decades.

Three hundred seventy-three IR prostate cancer patients treated with definitive RT between 5/2002–5/2016 were identified in an institutional review board approved database. All patients received conformal RT to the prostate while the vast majority did not receive nodal radiation. ADT was commenced 2 months prior to RT and was continued for 4 months after RT.

Compared to RT alone, patients receiving combined RT+ ADT had more positive biopsy cores, higher pre-radiation PSA, more IR factors, and were more likely to receive pelvic lymph node radiation. However, there were no differences in failure either biochemical, local or distal, nor on survival between the favorable RT alone and the unfavorable RT+ ADT cohorts, suggesting a beneficial role for ADT. On multivariate analysis, patients 70 years or younger receiving RT alone were at increased risk for biochemical failure during a 6-year follow-up (HR 3.06, P = 0.025). Biochemical relapse free survival in patients ≤70 years who received RT alone was 82.1% vs 94.0% for RT + ADT (P = 0.030). There was no difference for combined treatment modality in patients > 70 years (P = 0.87).

Men 70 years or younger with favorable IR prostate cancer treated with RT alone to 78 Gy are at increased risk of biochemical failure. Short term ADT should be considered in this cohort of men.