Adjuvant Radiotherapy in Prostate Cancer Patients Treated with Surgery: The Impact of Age and Tumor Characteristics

Abstract

BackgroundThe overall mortality (OM) and cancer-specific mortality (CSM) benefits of adjuvant radiotherapy (aRT) in treating prostate cancer (PCa) patients with adverse pathologic characteristics at radical prostatectomy (RP) are unclear. ObjectiveTo test the impact of aRT on survival in PCa patients treated with RP according to adverse pathologic characteristics (Gleason score [GS] 8–10; pT3b/4, lymph node invasion [LNI]) and age categories (<70 vs ≥70 yr). Design, setting, and participantsA total of 7616 patients with pT3/4 pN0/1 PCa treated with RP between 1995 and 2009 within the Surveillance Epidemiology and End Results–Medicare linked database were included. Outcome measurements and statistical analysisCox regression analysis was used to test the relationship between aRT and CSM, as well as OM in the entire cohort. Stratification was performed according to tumor characteristics and age categories. Results and limitationsIn patients with fewer than two adverse pathologic characteristics, aRT did not improve CSM or OM. Conversely, in patients with two or more adverse pathologic characteristics, the 10-yr CSM-free rate was 92% in patients treated with aRT versus 82% in patients treated without aRT (p<0.001). This survival improvement was confirmed in patients aged <70 yr (p=0.01) but not in those ≥70 yr (p=0.1). In multivariable analyses, aRT was an independent predictor of lower CSM risk (hazard ratio: 0.45; p=0.02) only among patients aged <70 yr with two or more adverse pathologic characteristics. Similar trends were observed when OM was examined as an end point. ConclusionsAge and tumor characteristics should be considered in the selection of optimal aRT candidates after surgery. Only patients aged <70 yr with two or more adverse pathologic characteristics (GS 8–10, pT3b/4, LNI) appear to benefit from aRT. Patient summaryThe usefulness of adjuvant radiotherapy after surgery for prostate cancer greatly depends on tumor characteristics and patient age. Only patients with advanced local tumor characteristics aged <70 yr seem to benefit from this treatment modality.