Salvage radiotherapy administered within two 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 six months, according to retrospective analysis published in the June 18 issue of the Journal of the American Medical Association.
Bruce J. Trock, PhD, from Johns Hopkins School of Medicine in Baltimore, and colleagues sought to quantify the relative improvement in prostate cancer–specific survival of salvage radiotherapy compared to no therapy after biochemical recurrence following prostatectomy, and to identify subgroups for whom salvage treatment is most beneficial.
The researchers performed a retrospective analysis of a cohort of 635 U.S. men undergoing prostatectomy from 1982-2004, followed up through Dec. 28, 2007, who experienced biochemical and/or local recurrence and received no salvage treatment (397 patients), salvage radiotherapy alone (160 patients) or salvage radiotherapy combined with hormonal therapy (78 patients).
With a median follow-up of six years after recurrence and nine years after prostatectomy, the investigators found that 116 men (18 percent) died from prostate cancer, including 89 (22 percent) who received no salvage treatment, 18 (11 percent) who received salvage radiotherapy alone, and 9 (12 percent) who received salvage radiotherapy and hormonal therapy.
Trock and colleagues found that salvage radiotherapy alone was associated with a significant three-fold increase in prostate cancer–specific survival relative to those who received no salvage treatment. The addition of hormonal therapy to salvage radiotherapy was not associated with any additional increase in prostate cancer–specific survival, the authors wrote.
The researchers found that 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 six months and remained after adjustment for pathological stage and other established prognostic factors.
Salvage radiotherapy initiated more than two years after recurrence provided no significant increase in prostate cancer–specific survival, Trock and colleagues wrote. Men whose prostate-specific antigen level never became undetectable after salvage radiotherapy did not experience a significant increase in prostate cancer–specific survival.
Based on their findings, the investigators concluded that “salvage radiotherapy also was associated with a significant increase in overall survival.”
However, Trock and colleagues noted that their “preliminary findings should be validated in other settings, and ultimately, in a randomized controlled trial.”