Presalvage prostate-specific antigen (PSA) and PSA doubling time as predictors of biochemical failure of salvage cryotherapy in patients with locally recurrent prostate cancer after radiotherapy

BACKGROUND. The value of presalvage cryotherapy serum PSA level in predicting biochemical failure in patients with local recurrence of prostate cancer (PCa) after radiotherapy was documented; however, little is known about the predictive value of prostate-specific antigen (PSA) doubling time (DT) in this patient group. The purpose of the current study was to evaluate serum PSA level and PSA DT as predictors of salvage cryotherapy outcomes in patients being treated for postradiotherapy locally recurrent PCa. METHODS. The charts of patients treated with salvage cryotherapy were retrospectively reviewed for locally recurrent PCa at the M. D. Anderson Cancer Center from January 1980 to July 2004. Patients who received neoadjuvant or adjuvant hormone therapy were excluded. We assessed pre- and postradiotherapy clinical data, pre- and postsalvage cryotherapy clinical data, and other variables. Kaplan-Meier and log rank tests were performed to assess unadjusted survival probabilities and 2-group survival comparisons, respectively. Cox proportional hazards regression models were used to assess the effect of patient characteristics in predicting overall, disease-specific, and biochemical failure-free survival. RESULTS. Forty-nine patients met the eligibility criteria. The median age of patients at diagnosis was 66 years (58-81 years) with the initial clinical stage before radiotherapy most commonly T2 (n = 5) or T3 (n = 21). The median presalvage cryotherapy serum PSA level was 5.9 ng/mL (0.4-23.1 ng/mL) and the presalvage prostatic biopsies were frequently high grade (Gleason grade ≥8 in 51% of patients). The median postsalvage cryotherapy serum PSA level was 0.1 ng/mL (0.1-9.5 ng/mL), and biochemical failure (defined as a serum PSA level ≥2 ng/mL above the postsalvage cryotherapy PSA nadir) occurred in 26 patients. In these 26 patients, there was a statistically significant difference between pre- and postsalvage cryotherapy PSA DTs (12.3 months to 5.6 months, respectively; P = .02). A presalvage cryotherapy serum PSA level >10 ng/mL (P = .002) and PSA DT ≤16 months (P = .06) were found to predict the subsequent risk of biochemical failure. CONCLUSIONS. Presalvage PSA and PSA DT can predict biochemical failure of salvage cryotherapy, although the predictive value of PSA DT only trended toward significance. The statistically significant difference in pre- and postsalvage cryotherapy PSA DTs was reflective of aggressive tumor biology.