Adjuvant radiation therapy is associated with better oncological outcome compared with salvage radiation therapy in patients with pN1 prostate cancer treated with radical prostatectomy

Abstract

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 (PCa) after radical prostatectomy (RP).

Patients and methods: A total of 773 patients with LN-positive PCa 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 PCa 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.

Keywords: adjuvant radiation therapy; lymph node metastasis; oncological outcome; prostate cancer; radical prostatectomy; salvage radiation therapy.