PSA doubling time of 6 months or less and seminal vesicle invasion predicted an inadequate response.
For these high-risk PCa patients, androgen deprivation could be considered, suggested the research team led by Einar Servoll, MD, of Sørlandet County Hospital in Norway.
For the study, published online ahead of print in the Scandinavian Journal of Urology, the investigators reviewed the medical records of 76 hospital patients treated with salvage EBRT following radical prostatectomy. They examined PSA values, operative and pathology reports, and radiographic staging studies.
The researchers calculated PSA doubling time prior to salvage radiotherapy and chose a dividing line of 6 months because a previous study found it meaningful.
Most patients were treated with a radiation dose of 70 Gy; 8 received a dose of 60 to 64 Gy. None of the patients received androgen deprivation therapy (ADT).
After a median of 82 months (maximum 16 years), 17 patients experienced biochemical recurrence, 7 developed metastatic disease, and 2 died of PCa.
Biochemical-free recurrence rates after salvage EBRT at 50 months and 75 months were 84% and 79%, respectively.
PSA doubling time of 6 months or less and seminal vesicle invasion in the prostatectomy specimen were significant predictors of biochemical recurrence.
The researchers noted that the RADICALS study, in progress, may further illuminate salvage treatment for PCa. It is exploring outcomes for patients randomly assigned to salvage radiotherapy with or without ADT.