Predicting men at high risk for PSA failure after salvage radiotherapy for rising PSA following prostatectomy

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4570 Background: Single and multi-institutional reports have published results indicating 5-year PSA response rates of 30 to 50% in men following salvage radiotherapy (RT) for rising PSA after radical prostatectomy (RP) depending upon the patient and disease factors. We analyzed a longitudinal observational database of men who received salvage RT following RP for their prostate cancer to evaluate for predictors of PSA failure despite salvage RT. Methods: Data from the Cancer of the Prostate Strategic Urologic Research Endeavor database (CaPSURE) identified 5,336 men with RP between 1989 and 2004; 200 underwent salvage RT ≥6 months after RP. PSA recurrence following salvage RT was defined as a PSA >0.2 ng/mL. A measure of the association between clinical and pathologic characteristics in men experiencing PSA failure following salvage RT was examined using a chi-square metric. Univariable and multivariable analyses of predictors for PSA recurrence using a Cox proportional hazard regression model were performed. Results: After a mean follow-up of 18 months (range 1 to 131 months), 121 (62%) men experienced PSA recurrence at a mean 13.7 months after salvage RT. Significant associations between time to PSA recurrence after salvage RT were found with the clinical risk group (p < .01), clinical T category (p < .01), race/ethnicity (p = .04), extraprostatic extension (p < .01), seminal vesicle invasion (p < .01), and pre-salvage RT PSA level (p < .01). The pre-salvage RT PSA level (p = .003) and seminal vesicle invasion (p = .02) remained significantly associated with time to PSA recurrence on multivariable analysis. Conclusions: The pre-salvage RT PSA level and the presence of seminal vesicle invasion were significantly associated with time to PSA recurrence following salvage RT within the CaPSURE database. Men with these risk factors are at increased risk for PSA recurrence despite salvage RT suggesting that these men would be ideal candidates for entry onto phase III studies comparing salvage RT plus systemic therapy with salvage RT alone at the time of post-operative PSA failure. [Table: see text]