Pulmonary complications following different radiotherapy techniques for breast cancer, and the association to irradiated lung volume and dose

Purpose. This study investigates the incidence of short-term pulmonary comp lications following radiotherapy (RT) for breast cancer (BC) with different treatment techniques/incidentally irradiated lung volumes and the importan ce of confounding factors on RT-induced pulmonary complications. Patients and methods. Prospectively, 475 patients with BC were followed for pulmonary complications 1, 4 and 7 months post-RT. Mean lung dose volume h istograms (MDVH) were constructed and compared for the different RT-techniq ues. Among a subset of the mastectomized patients treated with loco-regiona l (LR-) RT, who had undergone complete three-dimensional (3-D) dose plannin g (n= 43), MDVH for asymptomatic patients was compared with MDVH for patien ts experiencing both radiological and clinical pulmonary side-effects. Results. Moderate pulmonary complications, that is requiring treatment with corticosteroids, were rare following local RT ( < 1%), but were diagnosed among 11% of the patients treated with LR-RT. A correlation between increas ing irradiated lung volumes at the > 20 Gy-level (V(2)0), based on MDVH for the RT-techniques, and pulmonary complications was found (P < 0.001). Furt hermore, increasing age and reduced pre-RT functional level were independen tly associated with a higher rate of pulmonary complications (P = 0.005 and P = 0.018). Among the subgroup of mastectomized patients treated with LR-R T, who had undergone complete 3-D dose planning, a difference in mean V(2)0 was found between patients experiencing both clinical and radiological pul monary side-effects compared to patients experiencing neither of the two si de-effects (P = 0.007). Conclusion. Moderate pulmonary complications following local RT for BC are rare. The incidence of short-term moderate pulmonary complications in LR-RT is, however, clinically significant and to define quality assurance guidel ines for these RT-techniques, 3-D RT planning can be used.