Not All Adverse Pathology Features Are Equal: Identifying Optimal Candidates for Adjuvant Radiotherapy Among Patients With Adverse Pathology at Radical Prostatectomy

Abstract

Purpose: Recent studies reported a potential benefit associated with adjuvant radiotherapy for patients with adverse pathology features of prostate cancer. We hypothesized that not all the patients with adverse features may benefit from adjuvant radiotherapy and, therefore, observation ± early salvage radiotherapy 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 adjuvant radiotherapy for each risk subgroup after adjusting for inverse probability of treatment weighting.

Results: Overall, 538 (58%) vs 89 (10%) vs 299 (32%) patients received adjuvant radiotherapy vs early salvage radiotherapy vs observation. The 10-year overall survival rate was 90%. A significant interaction between adjuvant radiotherapy and high-risk group was recorded (HR 0.21, P = .04). After risk stratification and propensity-score weighting, survival analyses depicted comparable 10-year overall survival in low- and intermediate-risk patients treated with adjuvant radiotherapy or observation ± early salvage radiotherapy. Conversely, in high-risk patients, adjuvant radiotherapy was associated with significant improvement in 10-year overall survival compared to observation ± early salvage radiotherapy (76% vs 63%, P = .038).

Conclusions: Among patients with adverse pathology features, we identified 3 subclassifications of risk. When testing the effect of adjuvant radiotherapy vs observation with or without early salvage radiotherapy on survival, only patients included in the high-risk group seemed to benefit from adjuvant radiotherapy.

Keywords: prostatectomy; prostatic neoplasms; radiotherapy, adjuvant; recurrence; salvage therapy.