A RANDOMIZED STUDY OF 2 DOSES OF ABDOMINOPELVIC RADIATION-THERAPY FORPATIENTS WITH OPTIMALLY DEBULKED STAGE-I, STAGE-II, AND STAGE-III OVARIAN-CANCER

Purpose: To determine whether an increased dose of abdominal radiation therapy results in improved disease control and survival in patients with early ovarian cancer. Methods and Patients: Between 1981 and 1990 , 125 patients with optimally debulked Stage I, II, and III ovarian ca ncer were entered into a prospective randomized clinical trial of abdo minopelvic radiation therapy. Patients were stratified and randomized to either the control arm, treated with an abdominal dose of 22.5 Gy i n 22 fractions, or the experimental arm of 27.5 Gy in 27 fractions. A pelvic boost dose of 22.5 Gy was used in both arms. There were 43 pati ents with Stage I tumors, 71 Stage II tumors, and 11 Stage III tumors. Nineteen patients had grade 1 histology, 77 grade 2, and 29 grade 3. Three patients had small-volume residual disease (<2 cm) in the pelvis alone and the remainder had no gross tumor following surgery. Median follow-up was 6.6 years (range 1.4-9.9). Results: Overall survival (OS ) at 5 years was 83% in the low-dose arm and 72% in the high-dose arm (p = 0.3). Disease-free survival (DFS) at 5 years was 74% and 67% in t he low-dose and high-dose arms, respectively (p = 0.5). The difference in OS between the two arms was -11%, with 95% confidence intervals of -26% (favoring low-dose treatment) to 4% tin favor of high dose). The difference in DFS was -7% (95% confidence interval, -23 to 9%). Failu re in the pelvis alone predominated (n = 15); six patients had abdomin al and pelvic failure and seven patients failed in the abdomen alone. There were no differences in patterns of relapse, hematologic toxicity , or late complications between the two arms. Serious bowel toxicity w as seen in three patients: two in the low-dose and one in the high-dos e arm. A Cox proportional hazards model was used to assess the effect of treatment when adjusting for other prognostic variables. Ascites (p = 0.03, relative risk 2.05) was the only significant covariate in pre dicting disease-free survival, but was not prognostic for overall surv ival. Conclusions: There was no difference in survival, tumor control, or toxicity between high-dose and low-dose abdominopelvic radiation t herapy. High-dose abdominopelvic radiation therapy is unlikely to be a ssociated with an increase in OS of more than 4% or DFS of more than 9 %. (C) 1998 Elsevier Science Inc.