[Occurrence of organizing pneumonia after radiation therapy for postoperative breast cancer]

Three cases of organizing pneumonia (OP) that occurred after planned radiation therapy for postoperative breast cancer are reported. All patients received tangential radiation therapy and adjuvant tamoxifen (TAM) for postoperative breast cancer. Two patients developed fever and cough; one was asymptomatic. Chest radiography and computed tomography demonstrated peripheral alveolar opacities outside the radiation field. Bronchoalveolar lavage showed an elevated total cell count with a high percentage of lymphocytes, as well as elevated eosinophil levels in two cases. Transbronchial lung biopsy revealed a histologic pattern consistent with organizing pneumonia. For the two symptomatic cases, treatment with corticosteroids reduced clinical symptoms promptly and improved imaging findings. The single asymptomatic case improved without treatment. The number of such reported cases has increased in recent years, but the etiology is unclear. In the three cases presented, TAM combined with radiation therapy may have been the cause of the OP.