Objectives: To determine whether pretreatment risk groups also predict for posttreatment prostate-specific antigen (PSA) doubling times (PSADTs). Pretreatment risk groups predict for posttreatment biochemical failure (BF) after conformal radiotherapy in patients with prostate cancer and posttreatment PSADTs can predict for prostate cancer-related deaths.
Methods: The study cohort consisted of 416 patients with clinically localized prostate cancer treated with conformal radiotherapy between 1989 and 2001. The patients were divided into low, intermediate, and high-risk groups. BF was defined using the American Society for Therapeutic Radiology and Oncology consensus definition. Patients with BF were grouped according to their PSADT (3 months or less, longer than 3 months to less than 6 months, 6 months to less than 12 months, and 12 months or longer). A Mantle-Haenszel chi-square metric tested for an association between the pretreatment risk group and the PSADT. Logistic regression multivariate analysis was performed to evaluate whether the pretreatment risk group predicted the PSADT.
Results: Of the 416 patients, 96 (23%), 194 (47%), and 126 (30%) were categorized as low, intermediate, and high risk, respectively. A total of 92 patients (22%) experienced BF. Of these 92 patients, the PSADT was 3 months or less in 6 (7%), longer than 3 months to less than 6 months in 13 (14%), 6 months to less than 12 months in 35 (36%), and 12 months or longer in 38 (41%). The pretreatment risk group correlated significantly with the PSADT (P = 0.026). Logistic regression analysis revealed that intermediate and high-risk disease was significantly associated with shorter PSADTs (P = 0.039).
Conclusions: A significant association between the pretreatment risk group and posttreatment PSADT was demonstrated. Use of this selection criterion at diagnosis for more aggressive treatment appears warranted.