RADIATION-ASSOCIATED MORBIDITY IN PATIENTS UNDERGOING SMALL-FIELD EXTERNAL-BEAM IRRADIATION FOR PROSTATE-CANCER

Purpose: To quantify complication rates after small-field external bea m irradiation for adenocarcinoma of the prostate in a uniformly treate d patient population with long follow-up using a simple tool designed to identify subtle treatment-related side effects; and to identify cli nical and technical variables associated with increased morbidity afte r irradiation. Methods and Materials: A total of 441 patients with non metastatic adenocarcinoma of the prostate treated at the Joint Center for Radiation Therapy between 1985 and 1989 were eligible for analysis . Gastrointestinal, genitourinary, and sexual function were assessed r etrospectively using a patient self-scoring, five-grade toxicity scale . Seven clinical and 15 technical variables were recorded for each pat ient. The association between the clinical and technical variables and rectal, bladder, and sexual side effects was examined. The 375 patien ts who received small-field (<12.5 x 12.5-cm) external beam irradiatio n via a four-field box on a 6-MV (n = 74, or 20% of patients), 8-MV (n = 140, or 37%), or 15-MV (n = 161, or 43%) linear accelerator form th e basis for the study. Ninety-one percent of patients received treatme nt with 1.8-2.0 Gy fractions to a delivered dose of at least 66 Gy. Fo llow-up was complete through 62 months in living patients, with five ( 1%) of the entire group lost to follow-up. Results: A total of 137 of 354 evaluable patients (39%) reported rectal complications after treat ment; however, 20 patients(6%) had heme-positive stools as their only symptom and 66 (19%) had mild symptoms not requiring treatment. Only 1 4% of the entire group required intervention. Of 356 patients, 117 (33 %) evaluable for bladder complications developed genitourinary changes : In 14 patients (4%) asymptomatic hematuria occurred, 71 (20%) had mi ld symptoms not requiring treatment, and 32 (9%) required treatment. O f the 171 patients who were potent prior to radiation, 106 (62%) repor ted impotence after treatment. No statistically significant associatio n was identified between any clinical or technical variables (includin g machine energy) assessed and complications. Conclusions: In this ret rospective review, treatment-related bowel and bladder side effects me re not identified in the majority of patients despite the use of a gra ding system designed to identify subtle changes. Impotence, however, w as common. Although pretreatment clinical characteristics varied among patients, they could not be used to predict the subsequent developmen t of complications. The only treatment-related characteristic that var ied in this study was machine energy, which did not correlate with com plications. (C) 1998 Elsevier Science Inc.