Carcinoma of the prostate stage B and C: lack of influence of duration of radiotherapy on tumor control and treatment morbidity.

Between 1966 and 1985, 542 of 585 patients with histologically confirmed carcinoma of the prostate, Stages B and C, were treated with definitive radiation therapy to a minimum of 6300 cGy. There were 191 Stage B patients and 351 Stage C patients. The median tumor dose for Stage B patients was 6957 cGy and for Stage C patients 7020 cGy. Daily fractions of 180 to 200 cGy were given 4 or 5 times per week with occasional rest periods of several days, usually because of side effects of radiation therapy. The minimum follow-up time was 3 years; maximum follow-up was 16.0 years, and the median was 4.8 years. In this analysis, within each stage, patients were divided into four groups based on the number of treatment days: less than or equal to 56 days (8 weeks), 57 to 63 days (9 weeks), 64 to 70 days (10 weeks), and greater than 70 days. The distribution of Stage B and Stage C patients by histologic grade and duration of therapy is fairly even within each group. The influence of duration of radiotherapy on actuarial survival, progression-free survival, pelvic control, and incidence of complications was analyzed, and no statistical difference among the four groups of patients was found. The scatterplots of pelvic failure by radiation dose and duration of radiotherapy for both Stage B and C prostate carcinoma patients did not show a correlation between failure rate and duration of radiotherapy. Tumor histologic grade did not influence the incidence of pelvic failure. In summary, within the dose range used in this analysis the overall length of radiation treatment time did not seem to affect the clinical outcome of patients with Stage B and C prostate carcinoma.