# Salvage Radiotherapy for Relapsed Prostate Cancer after Radical Prostatectomy Is Associated with Normal Life Expectancy

## TL;DR

Salvage radiotherapy for prostate cancer recurrence after surgery can lead to normal life expectancy and slower cancer progression.

## Contribution

This study shows that salvage radiotherapy improves life expectancy and slows cancer progression in prostate cancer patients.

## Key findings

- Salvage radiotherapy significantly prolonged PSA doubling times, indicating slower cancer progression.
- Patients receiving salvage radiotherapy had similar overall survival to age-matched controls.
- Gleason score, pre-SRT PSA, and surgical margins were risk factors for biochemical progression but not for overall survival.

## Abstract

Radiotherapy is a treatment option for prostate cancer patients who have increasing prostate-specific antigen values after prostatectomy. However, this treatment has never been compared directly in a single study with the course of untreated relapsed prostate cancer. We analyzed the course of prostate-specific antigen values before and after radiotherapy by calculating prostate-specific antigen doubling times. Prolongation of these values after radiotherapy indicated slower progression with this treatment. The survival analysis also suggests the advantages of salvage radiotherapy. In our analysis, when comparing our cohort with an age-matched cohort from life tables, it was observed that patients had a normal life expectancy after radiotherapy for recurrent prostate cancer following prostatectomy.

In patients with prostate cancer (PCa), salvage radiotherapy (SRT) for biochemical progression (BP) after radical prostatectomy (RP) improves PCa-specific survival. However, no prospective randomized trials have compared the effect of SRT with untreated patients. In this analysis of 151 patients who received SRT for post-RP BP, we compared their overall survival (OS) with virtual, age-matched controls (n = 151,000) retrieved from government life tables. We also investigated the risk factors associated with BP and OS and compared the prostate-specific antigen (PSA) doubling times (DTs) before and after SRT for patients with BP. The median follow-up was 9.3 years for BP and 17.4 years for OS. The risk factors significantly affecting BP were Gleason score (p < 0.001), pre-SRT PSA (p = 0.003), and negative surgical margins (p = 0.003). None of these risk factors were associated with OS. In 93 patients with BP after SRT, the median PSADT was significantly prolonged compared with pre-SRT values (3.7 vs. 8.3 months, p < 0.001). The OS did not differ between patients and controls (p = 0.112), and life expectancy was similar, likely due to the survival benefit of SRT. The prolonged PSADT after SRT further supports the beneficial role of SRT in this patient population. However, subsequent treatments were not systematically recorded, which may have affected the results.