Clinical factors predicting the outcome of salvage radiotherapy for patients with biochemical recurrence after radical prostatectomy.

Abstract

It remains unclear which patients with biochemical recurrence after prostatectomy are most suitable for salvage radiotherapy. We evaluated the parameters related to outcomes. We retrospectively evaluated patients who underwent salvage therapy for biochemical recurrence after prostatectomy between 2005 and 2019. This study aimed to evaluate biochemical recurrence-free survival (bRFS) after salvage radiotherapy and elucidate the parameters associated with bRFS. The bRFS rate was calculated using the Kaplan-Meier method, and the parameters associated with bRFS were evaluated using Cox regression analysis. This study included 67 patients treated with salvage radiotherapy with a median age of 67years at salvage radiotherapy. The median follow-up period after salvage radiotherapy was 7.3years. The 5-year bRFS rate following salvage radiotherapy was 47.1%. Univariate analysis showed that PSA doubling time < 6months, positive surgical margin, and pathological Gleason score ≥ 8 were significantly associated with shorter bRFS (p < 0.001, p = 0.036, p = 0.047, respectively). Multivariable analysis showed that a PSA doubling time < 6months and positive surgical margins were significantly associated with shorter bRFS (p = 0.001 and p = 0.018, respectively). No serious adverse events were observed. In our hospital, approximately half of the patients are under long-term control with salvage radiotherapy. A PSA doubling time of < 6months and positive surgical margins were suggested to be associated with poor outcomes of salvage radiotherapy.