Relative influence of Gleason score and pretreatment PSA in predicting survival following brachytherapy for prostate cancer

PURPOSE: To evaluate 10-year survival rates after prostate brachytherapy and to assess the relative importance of pretreatment prostate-specific antigen (PSA) and Gleason score in predicting cancer death. MATERIALS AND METHODS: A retrospective review was performed on all patients treated with permanent brachytherapy for stage T1 or T2 primary prostate cancer at a single institution from December 1988 through June 30, 1998. The study cohort consisted of 1266 patients with a median follow-up of 4.1 years and a maximum of 12.6 years. Actuarial survival and cause-specific survival rates were calculated as the primary endpoints, and compared at 5 and 10 years. Groups studied consist of PSAor=10 as well as Gleason 2-4, 5-6, and 7-10. Multivariate and univariate analysis were performed looking at stage, grade, PSA, and risk group as variables. RESULTS: The median age at the time of treatment was 73 years and at the time of analysis 603 patients were known to be alive. Overall survival is 38% at 10 years, however most deaths were unrelated to prostate cancer. Cause specific survival at 5 and 10 years is 98% and 87%. Both grade (>or=Gleason 7) and PSA (>or=10 ng/ml) predict adversely for cancer death within 10 years. Patients with low grade or PSA at presentation reveal prostate cancer-specific survival of 91% and 98%, respectively. By contrast, men with high grade or high PSA presentation have survival of 66% and 69% at 10 years. In multivariate analysis, the presence of one of these adverse features carries a hazard ratio of cancer death of 4.7 and 6.4, while the presence of multiple risk factors places patients in an unfavorable risk group with a hazard ratio of 27. CONCLUSIONS: Biochemical disease-free survival is a useful tool to assess prostate cancer treatments and is predicted based on established pretreatment risk groups. Long-term cancer-specific survival is ultimately a more important endpoint. Brachytherapy is reported here to be an excellent therapeutic alternative for selected early stage patients with prostate cancer. This is based on 10-year cause specific survival, which may also be predicted by stage, grade, PSA, and risk group. Of these, the risk group remains the most powerful parameter to identify those patients at highest risk of biochemical failure and death from prostate cancer.