Incidence of infectious symptoms after radiation therapy for breast cancer

The incidence of symptoms generally associated with infectious disease was assessed by a questionnaire sent out to 519 disease-free breast cancer patients 7 to 12 years after primary treatment. All patients were treated in the context of a randomized trial where pre- and postoperative radiation (45 Gy) was evaluated versus surgery only. The results indicate a significantly higher morbidity among patients treated with preoperative irradiation compared with those irradiated postoperatively (p<0.05). This increased morbidity mainly seemed to be caused by symptoms usually associated with respiratory tract infection (p<0.05). Although statistically not significant the preoperatively irradiated patients also had a higher morbidity than those treated with surgery alone. There was no difference between postoperatively irradiated patients and patients treated with surgery only. A significantly higher integral dose (absorbed energy within the body) of the pre- compared with the postoperative group (p<0.025) is associated with the differences in morbidity between the two irradiated groups. An explanation for the increased morbidity seems to be that the volume of lung tissue, encompassed within the full-dose target volume, is the crucial factor. This volume was considerable in the preoperative treated patients but kept at a minimum in the postoperative group. (orig.)