Adjuvant radiation therapy is associated with better oncological outcome compared with salvage radiation therapy in patients with pN 1 prostate cancer treated with radical prostatectomy

Objective To analyse the comparative effectiveness of no treatment ( NT ) or salvage radiation therapy ( sRT ) at biochemical recurrence ( BCR ) vs adjuvant radiation therapy ( aRT ) in patients with lymph node ( LN )‐positive prostate cancer ( PC a) after radical prostatectomy ( RP ). Patients and Methods A total of 773 patients with LN ‐positive PC a at RP , with or without additional radiation therapy ( RT ), in the period 2005–2013, were retrospectively analysed. Cox regression analysis was used to assess factors influencing BCR and metastasis‐free survival ( MFS ). Propensity score‐matched analyses were performed. Results The median follow‐up for the entire patient group was 33.8 months. Four‐year BCR ‐free and MFS rates were 43.3% and 86.6%, respectively, for all patients. In multivariate analysis, NT / sRT ( n = 505) was an independent risk factor for BCR and metastasis compared with aRT ( n = 213). The superiority of aRT was confirmed after propensity score matching. The 4‐year MFS in the matched cohort was 82.5% vs 91.8% for the NT / sRT and aRT groups, respectively ( P = 0.02). Early sRT (pre‐ RT prostate‐specific antigen [ PSA ] ≤0.5 ng/ mL ) compared with sRT at PSA >0.5 ng/ mL was significantly associated with a lower risk of metastasis. Conclusion Patients with LN ‐positive PC a who received aRT had a significantly better oncological outcome than patients with NT / sRT , independent of tumour characteristics. Patients with early sRT had higher rates of response and better MFS than patients with pre‐ RT PSA >0.5 ng/ mL .