Watchful Waiting and Factors Predictive of Secondary Treatment of Localized Prostate Cancer

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Abstract
Watchful waiting remains an important treatment option for some patients with localized prostate cancer. We defined the demographic, clinical and outcome features of men selecting watchful waiting as an initial treatment strategy, and determined factors predictive of eventual progression to secondary treatment. Of 8390 patients diagnosed with prostate cancer from 1990 to 2001 in the Department of Defense Center for Prostate Disease Research Database, 1158 patients chose watchful waiting as initial treatment. The demographic and clinical differences between patients on watchful waiting and those choosing other initial treatments were compared using the chi-square test. Secondary treatment-free survival according to various prognostic factors was plotted using the Kaplan-Meier method and differences were tested using the log rank test. A multivariate Cox proportional hazards regression analysis was performed to determine which factors were independent predictors of secondary treatment. Compared to other patients, those selecting watchful waiting were older, had lower prostate specific antigen (PSA) at diagnosis, and were more likely to have lower stage (cT1) and lower grade (Gleason sum 7 or less) cancers. Age, PSA and clinical stage were all significant and independent predictors of secondary treatment. The relative risk of secondary treatment can be expressed as EXP (-0.034 x age at diagnosis + 0.284 x LOG (diagnostic PSA) + 0.271 x clinical stage T2 + 0.264 x clinical stage T3). Men who elect watchful waiting as initial management for prostate cancer are older with lower Gleason sums and serum PSA. In these men, age at diagnosis, serum PSA and clinical stage are the most significant predictors of requiring or selecting secondary treatment.