Objectives: To determine the predictive factors of prostate-specific antigen (PSA) recurrence after salvage radiotherapy (RT) for biochemical recurrence following radical prostatectomy (RP) to identify patients who may benefit from this treatment.
Methods: From June 1992 to January 2002, 62 patients experiencing PSA recurrence after RP were treated with RT at a dose of 65 Gy. No patient received hormonal therapy. PSA recurrence after RT was defined as three consecutive increased PSA measurements. The risk of experiencing PSA recurrence after RT was analyzed according to 10 factors: patient age, pre-RP PSA level, pathologic stage, Gleason score, surgical margin status, PSA nadir after RP, time to PSA recurrence after RP, pre-RT PSA level, PSA nadir after RT, and length of follow-up after RT.
Results: With a mean follow-up of 44 months (range 3 to 110), 23 patients (37.1%) experienced PSA recurrence after RT. Using univariate analysis, six factors were found to be predictive of PSA recurrence after RT: the length of follow-up after RT (P <0.0001), PSA nadir after RP (P = 0.0004), time to PSA recurrence after RP (P = 0.003), pre-RP PSA level (P = 0.008), Gleason score (P = 0.011), and pre-RT PSA level (P = 0.028). Using multivariate analysis, only the Gleason score (P = 0.015) and length of follow-up after RT (P = 0.02) were found to be predictive of PSA recurrence after RT. A Gleason score greater than 7 was a significant predictor of PSA recurrence after salvage RT (P = 0.04).
Conclusions: In our experience, the Gleason score and length of follow-up were the sole independent predictors of PSA recurrence after salvage RT. Our findings suggest that patients with a Gleason score of 7 or less are more likely to benefit from salvage RT after RP and that the durability of the PSA response may be only transient.