Failure patterns and hazard rates for failure suggest the cure of prostate cancer by external beam radiation.

OBJECTIVES: To present patterns of failure and hazard rates for failure that support the concept of cure for patients with prostate cancer treated with external beam radiation (RT).
METHODS: Two patient groups are reported: 408 patients treated with RT alone and 63 patients treated with RT and short-term androgen deprivation (RT+AD). All patients were treated between March 1987 and March 1995 and had at least 4 years of prostate-specific antigen (PSA) follow-up. The median follow-up was 69 months for the RT alone group and 60 months for the RT+AD group. For each treatment group, biochemical control and hazard functions were estimated using the ASTRO consensus definition of failure and the life table method.
RESULTS: The 5 and 8-year biochemical control estimates were 60% and 59% for the RT alone group, respectively, with only two failures occurring after 5 years (1% of the total failures observed). Hazard function estimates indicated a maximum risk of failure at 12 to 36 months, tapering to a low rate at 4 years, with no failures observed after 6 years. The differences in the patterns of failure by PSA level revealed a maximum risk of failure at 12 to 24 months (median 28) for a pretreatment PSA level of less than 10 ng/mL, 12 to 36 months (median 25) for a pretreatment PSA level of 10 to 19.9 ng/mL, and 12 to 36 months (median 22) for a pretreatment PSA level of 20 ng/mL or greater. The latter group reached low levels of risk at 6 years in contrast to 4 years for the patients presenting with pretreatment PSA levels of less than 20 ng/mL. Similar patterns were observed when stratifying by stage and Gleason score: patients with a worse prognosis had the highest risk of failure earlier and achieved a low risk of failure later than patients with a more favorable prognosis. The patients in the RT+AD group had a different pattern of risk of failure, with the highest risk immediately after treatment, declining to a low risk of failure at 48 months.
CONCLUSIONS: Patients treated with RT alone or RT+AD had little risk of failure after 4 to 6 years. Patients with a favorable prognosis achieved a low risk of failure sooner than high-risk patients when treated with RT alone. These results are consistent with the cure of prostate cancer by RT alone or RT+AD.