Radiation therapy for clinically localized prostate cancer - A multi-institutional pooled analysis

Context Prostate-specific antigen (PSA) evaluation leads to the early detec tion of both prostate cancer and recurrences following primary treatment. P rostate-specific antigen outcome information on patients 5 or more years fo llowing treatment is limited and available mainly as single-institution rep orts. Objectives To assess the likelihood and durability of tumor control using P SA evaluation 5 or more years after radical external beam radiation therapy and to identify pretreatment prognostic factors in men with early prostate cancer treated since 1988, the PSA era. Design and Setting Retrospective, nonrandomized, multi-institutional pooled analysis of patients treated with external beam radiation therapy alone be tween 1988 and 1995 at 6 US medical centers. Follow-up lasted up to a maxim um of 9 years. Outcome data were analyzed using Cox regression and recursiv e partitioning techniques. Patients A total of 1765 men with stage T1b, T1c, and T2 tumors treated bet ween 1988 and 1995 with external beam radiation. The majority (58%) of pati ents were older than 70 years and 24.2% had initial PSA values of 20 ng/mL or higher. A minimum of 2 years of subsequent follow-up was required for pa rticipation, Main Outcome Measure Actuarial estimates of freedom from biochemical failur e. Results The 5-year estimates of overall survival, disease-specific survival , and the freedom from biochemical failure are 85.0% (95% confidence interv al [CI], 82.5%-87.6%), 95.1% (95% CI, 94.0%-96.2%), and 65.8% (95% CI, 62.8 %-68.0%), respectively, The PSA failure-free rates 5 and 7 years after trea tment for patients presenting with a PSA of less than 10 ng/mL were 77.8% ( 95% CI, 74.5%-81.3%), and 72.9% (95% CI, 67.9%-78.2%). Recursive partitioni ng analysis of initial PSA level, palpation stage, and the Gleason score gr oupings yielded 4 separate prognostic groups: group 1, included patients wi th a PSA level of less than 9.2 ng/mL; group 2, PSA level of at least 9.2 b ut less than 19.7 ng/mL; group 3, PSA level at least 19.7 ng/mL and a Gleas on score of 2 to 6; and group 4, PSA level of at least 19.7 ng/mL and a Gle ason score of 7 to 10. The estimated rates of survival free of biochemical failure at 5 years are 81% for group 1, 69% for group 2, 47% for group 3, a nd 29% for group 4. Of the 302 patients followed up beyond 5 years who were free of biochemical disease, 5.0% relapsed from the fifth to the eighth ye ar, Conclusions Estimated PSA control rates in this pooled analysis are similar to those of single institutions. These rates indicate the probability of s uccess for subsets of patients with tumors of several prognostic category g roupings. These results represent a multi-institutional benchmark for evide nce-based counseling of prostate cancer patients about radiation treatment.