Prostate cancer-specific survival following salvage radiotherapy vs observation in men with biochemical recurrence after radical prostatectomy.

Abstract

Biochemical disease recurrence after radical prostatectomy often prompts salvage radiotherapy, but no studies to date have had sufficient numbers of patients or follow-up to determine whether radiotherapy improves survival, and if so, the subgroup of men most likely to benefit. To quantify the relative improvement in prostate cancer-specific survival of salvage radiotherapy vs no therapy after biochemical recurrence following prostatectomy, and to identify subgroups for whom salvage treatment is most beneficial. Retrospective analysis of a cohort of 635 US men undergoing prostatectomy from 1982-2004, followed up through December 28, 2007, who experienced biochemical and/or local recurrence and received no salvage treatment (n = 397), salvage radiotherapy alone (n = 160), or salvage radiotherapy combined with hormonal therapy (n = 78). Prostate cancer-specific survival defined from time of recurrence until death from disease. With a median follow-up of 6 years after recurrence and 9 years after prostatectomy, 116 men (18%) died from prostate cancer, including 89 (22%) who received no salvage treatment, 18 (11%) who received salvage radiotherapy alone, and 9 (12%) who received salvage radiotherapy and hormonal therapy. Salvage radiotherapy alone was associated with a significant 3-fold increase in prostate cancer-specific survival relative to those who received no salvage treatment (hazard ratio [HR], 0.32 [95% confidence interval {CI}, 0.19-0.54]; P<.001). Addition of hormonal therapy to salvage radiotherapy was not associated with any additional increase in prostate cancer-specific survival (HR, 0.34 [95% CI, 0.17-0.69]; P = .003). The increase in prostate cancer-specific survival associated with salvage radiotherapy was limited to men with a prostate-specific antigen doubling time of less than 6 months and remained after adjustment for pathological stage and other established prognostic factors. Salvage radiotherapy initiated more than 2 years after recurrence provided no significant increase in prostate cancer-specific survival. Men whose prostate-specific antigen level never became undetectable after salvage radiotherapy did not experience a significant increase in prostate cancer-specific survival. Salvage radiotherapy also was associated with a significant increase in overall survival. Salvage radiotherapy administered within 2 years of biochemical recurrence was associated with a significant increase in prostate cancer-specific survival among men with a prostate-specific antigen doubling time of less than 6 months, independent of other prognostic features such as pathological stage or Gleason score. These preliminary findings should be validated in other settings, and ultimately, in a randomized controlled trial.