Maximal tumor diameter and the risk of PSA failure in men with specimen-confined prostate cancer

Objectives. To evaluate whether the maximal tumor diameter (MTD) is significantly associated with the time to postoperative prostate-specific antigen (PSA) failure. Methods. Between 1986 and 2002, 781 men with clinical Stage T1c-T2 prostate cancer underwent radical prostatectomy. The MTD was recorded as the maximal dimension of the largest single focus of cancer from all 3-mm step sections. The median follow-up was 5.4 years (range 0.1 to 14.9); 242 men (31%) experienced PSA failure. A Cox regression analysis was used to determine the predictors of time to postoperative PSA failure. Kaplan-Meier estimates of PSA failure-free survival were made, dichotomized about the median MTD value, and compared using a two-sided log-rank test. Results. The value of the MTD was significantly associated with the time to PSA failure (adjusted hazard ratio 1.04, 95% confidence interval 1.01 to 1.07, P = 0.004), controlling for preoperative PSA level (P < 0.0001), prostatectomy Gleason score (P < 0.0001), and T stage (P <0.0001). When margin status was added (P = 0.0004), the MTD approached statistical significance (P = 0.07). For patients with a preoperative PSA level of less than 10 ng/mL, prostatectomy Gleason score of 3 + 4 = 7 or less, Stage pT2-T3a, and negative margins, the value of the MTD significantly (P = 0.05) stratified the time to PSA failure, when dichotomized about the median value (13 mm), with 7-year PSA failure estimates of 17% versus 8%. Conclusions. Whether patients with traditionally low-risk but large MTD prostate cancer fare better when treated with adjuvant radiotherapy compared with salvage radiotherapy remains to be answered in the setting of a randomized trial.