Multiple small fractions per day versus conventional fractionation. Comparison of normal tissue reactions and effect on breast carcinoma.

Hyperfractionation (3 fractions of about 1.0 Gy/day) and conventional fractionation were compared in two studies. In the first, the acute skin reactions, erythema and pigmentation, and the development of telangiectasia were analysed on postoperatively irradiated bilateral parasternal fields in patients with breast carcinoma. In the second study, the tumour effect in patients with inoperable breast carcinoma was investigated under conditions of equivalent normal tissue reactions for both fractionation schedules. With hyperfractionation the late-responding normal tissue was spared relative to the acutely responding normal tissue about 5% in absorbed dose. Concerning the therapeutic effect on adenocarcinoma of the breast 3 X 1.0 Gy/day was not better than 1 X 2.4 Gy/day. These daily doses resulted in equivalent late effects as was predicted from the normal tissue study.