Radiotherapy alone for oropharyngeal carcinomas: the role of fraction size (2 Gy vs 2.5 Gy) on local control and early and late complications.

This retrospective study involved 150 patients treated for oropharyngeal carcinoma by external radiotherapy alone at the Institut Gustave-Roussy. The midplane tumor dose was 70 Gy delivered in 7 weeks. During 1981, 63 patients were treated with 5 fractions (5 F) of 2 Gy per week. The following year, 87 patients, were treated with 4 fractions (4 F) of 2.5 Gy per week. Prognostic factors were equally distributed in both groups. The locoregional tumor control was 83% for the 4 F patients and 83% for the 5 F patients. Degree and incidence of acute reactions with both fractionation regimens were similar. Necrosis of the oropharyngeal mucosa and trismus were significantly more severe and more frequent in the 4 F group (23% and 20% respectively) than in the 5 F group (10% and 5% respectively) (p = 0.03 and p = 0.01). Other late effects such as skin necrosis (6% in the 4 F group versus 0% in the 5 F group) and severe cervical sclerosis (12 vs 5%) were also more frequent in the 4 F group than in the 5 F group but the difference was not significant. The results suggest a greater sensitivity of late compared to early normal tissue effects and of tumor response to an increase in dose per fraction (from 2 Gy to 2.5 Gy) in oropharyngeal carcinoma.