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

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).

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.

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.

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.