Late effect of multiple daily fraction palliation schedule for advanced pelvic malignancies (RTOG 8502)

The purpose was to determine late complication incidence for pelvic palliation using accelerated multiple daily fraction radiation [Radiation Therapy Oncology Group (RTOG) 8502]. None of the patients with < 30 Gy (less than three courses) developed late toxicity. A total of 11/193 (6%) developed Grade 3+ late toxicity (nine Grade 3, on Grade 4, one Grade 5). Actuarial analysis of complication rate by survival time for Grades 3, 4, and 5 shows a cumulative incidence for complications after 6 months that plateaus at 6.9% by 18 months. The cumulative incidence for Grades 4 and 5 is 2.0% by 12 months. The difference in late effect for the 2-week rest vs. 4-week rest was not statistically different (p = .47). Patient factors evaluated for increased risk of late complications included prior surgeries, age, sex, KPS and primary. None were found to have significant statistical correlations with late effects. The crude late complications rate is 6%. Actuarial analysis using cumulative incidence shows 6.9% by 18 months. This represents a significant decrease in late complications from 49% seen with higher dose per fraction (10 Gy x 3) piloted by Radiation Therapy Oncology Group (7905) for a similar group of patients. Long-term analysis of late complication indicates this schedule can be used in the pelvis with relatively low incidence of complication. This schedule has significant logistic benefits and has been shown to produce good tumor regression and excellent palliation of symptoms. 14 refs., 4 figs., 4 tabs