Combined treatment using radiation therapy (RT) and androgen suppression
therapy (AST) is used to treat men with clinically localized adenocarcinoma
of the prostate, but outcome using this combined therapy compared with RT
alone is not known.
To determine the relative efficacy of RT plus AST vs RT alone among
men with clinically localized prostate cancer.
Design, Setting, and Patients
Retrospective cohort study of 1586 men with prostate cancer who were
treated between January 1989 and August 1999 using 3-dimensional conformal
RT with (n = 276) or without (n = 1310) 6 months of AST.
Main Outcome Measure
Relative risk (RR) of prostate-specific antigen (PSA) failure (defined
according to the American Society for Therapeutic Radiology and Oncology consensus
statement), by treatment and high-, intermediate-, or low-risk group based
on serum PSA level, biopsy Gleason score, and 1992 American Joint Commission
on Cancer clinical tumor category.
Estimates of 5-year PSA outcome after RT with or without AST were not
statistically different among low-risk patients (P
= .09), whereas intermediate- and high-risk patients treated with RT plus
AST had significantly better outcomes than those treated with RT alone (P<.001 and = .009, respectively). The RR of PSA failure
in low-risk patients treated with RT plus AST was 0.5 (95% confidence interval
[CI], 0.3-1.1) compared with patients treated with RT alone. The RRs of PSA
failure in intermediate-risk and high-risk patients treated with RT plus AST
compared with RT alone were 0.2 (95% CI, 0.1-0.3) and 0.4 (95% CI, 0.2-0.8),
Our data suggest a significant benefit in 5-year PSA outcomes for men
with clinically localized prostate cancer in intermediate- and high-risk groups
treated with RT plus AST vs those treated with RT alone. Results from prospective
randomized trials currently under way are needed to validate these findings.