Improved tolerance with two radiation fractions per day for treatment of abdominal and pelvic malignancies.

When major volumes of the abdomen are the tolerable dose is frequently limited by the tolerance of the small intestine and other gastrointestinal tissues. In an attempt to increase the tolerable dose, a twice-daily, 5 day/week fractionation scheme was used. One hundred and thirty-nine patients were started on treatment for abdominal and pelvic malignancies, of whom 124 received the planned dose, usually in the prescribed time. Fifty-five hundred to 6000 rad in about 8 weeks was administered to large volumes of the pelvis and abdomen, frequently with "boost" radiation to 7500 rad to limited volumes. Ninety percent of the patients were able to complete treatment without interruption. In 90% of all cases there were no late radiation-related complications. The acute reactions and late complications have been comparable to those incurred when total doses 20-30% less are administered with one fraction per day. The survival rates of these patients indicates a probable improvement in therapeutic ratio. The physical techniques, areas treated, and time-dose sequence are described. A detailed analysis by primary organ, patient characteristics, performance status, types of complications, cause of death, and survival characteristics is presented.