Radiation Therapy Oncology Group studies in carcinoma of the prostate

From 1976 to 1983, the Radiation Therapy Oncology Group (RTOG) conducted 2 large-scale phase III trials of extended field irradiation in patients with carcinoma of the prostate. The first, RTOG 75-06, was designed to test the value of elective periaortic irradiation in patients in whom the tumor extended beyond the gland, but remained limited to the pelvis, and the second, RTOG 77-06, was designed to test the value of elective pelvic irradiation in patients without evidence of spread beyond the prostate. The results indicated no apparent benefit from elective periaortic irradiation in patients with detectable disease confined to the pelvis and no apparent benefit from elective pelvic irradiation in patients with detectable disease confined to the prostate. Patients with extracapsular extension of the primary tumor and evidence of pelvic lymph node involvement demonstrated an outcome comparable to that in patients without evidence of lymphatic involvement. This observation may reflect a beneficial effect of pelvic irradiation in patients with nodal involvement. In contradistinction to elective irradiation of regional lymphatics, therapeutic irradiation (of the involved lymphatics) may prove strongly indicated. A prospective study testing this contention needs to be conducted. No significant correlation of treatment-related morbidity and treatment volume could be identified. Analysis of the various types of treatment-related morbidity as to the time of onset and clinical course indicated that these behave as different disease entities characterized by a specific pattern of appearance, clinical course, and prognosis. Of particular interest is the observation that most appear reversible. Doses in excess of 7,000 cGy to the prostate were associated with a significantly increased incidence of bowel morbidity.(ABSTRACT TRUNCATED AT 250 WORDS)