Recent studies reported a potential benefit associated with adjuvant radiotherapy (aRT) for patients with adverse pathology features of prostate cancer. We hypothesized that not all the patients with adverse features may benefit from aRT and, therefore, observation +/- early salvage radiotherapy (eSRT) may still be considered in a subgroup of these patients.
Materials and Methods
Among 8,362 patients treated with radical prostatectomy at a single center between 1987 and 2020, 926 eligible patients with adverse pathology features (ie, Grade group 4-5 with ≥pT3a stage and/or lymph node invasion) were identified. Cox models were used to assign a score to each feature. Patients were then stratified in low, intermediate and high-risk groups and interaction term analyses tested the impact of aRT for each risk subgroup after adjusting for inverse-probability of treatment weighting.
Overall, 538 (58%) vs. 89 (10%) vs 299 (32%) patients received aRT vs eSRT vs observation. The 10-year overall survival (OS) rate was 90%. A significant interaction between aRT and high-risk group was recorded (HR 0.21, p=0.04). After risk stratification and propensity-score weighting, survival analyses depicted comparable 10-year OS in low and intermediate-risk patients treated with aRT or observation +/- eSRT. Conversely, in high-risk patients, aRT was associated with significant improvement in 10-yr OS compared to observation +/- eSRT (76 vs 63%, p=0.038).
Among patients with adverse pathology features, we identified three subclassification of risk. When testing the effect of aRT vs observation with or without eSRT on survival, only patients included in the high-risk group seemed to benefit from aRT.