Context Prostate-specific antigen (PSA) evaluation leads to
the early detection of both prostate cancer and recurrences following
primary treatment. Prostate-specific antigen outcome information on
patients 5 or more years following treatment is limited and available
mainly as single-institution reports.
Objectives To assess the likelihood and durability of tumor
control using PSA 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 between 1988 and 1995 at 6 US medical
centers. Follow-up lasted up to a maximum of 9 years. Outcome data were
analyzed using Cox regression and recursive partitioning techniques.
Patients A total of 1765 men with stage T1b, T1c, and T2 tumors
treated between 1988 and 1995 with external beam radiation. The
majority (58%) of patients 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 participation.
Main Outcome Measure Actuarial estimates of freedom from
Results The 5-year estimates of overall survival, disease-specific
survival, and the freedom from biochemical failure are 85.0% (95%
confidence interval [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 treatment 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
partitioning analysis of initial PSA level, palpation stage, and the
Gleason score groupings yielded 4 separate prognostic groups: group 1,
included patients with a PSA level of less than 9.2 ng/mL; group 2, PSA
level of at least 9.2 but less than 19.7 ng/mL; group 3, PSA level at
least 19.7 ng/mL and a Gleason score of 2 to 6; and group 4, PSA level
of at least 19.7 ng/mL and a Gleason 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, and 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 year.
Conclusions Estimated PSA control rates in this pooled analysis
are similar to those of single institutions. These rates indicate the
probability of success for subsets of patients with tumors of several
prognostic category groupings. These results represent a
multi-institutional benchmark for evidence-based counseling of prostate
cancer patients about radiation treatment.