Bronchiolitis Obliterans Organizing Pneumonia after Breast Cancer Radiotherapy and letrozole: A Case Report and Literature Review

Objectives: Bronchiolitis obliterans organizing pneumonia occurs with prevalence rate 1–3% after breast conservative treatment in series. In response to radiation of a lung or surrounding tissues, an inflammatory reaction can affect both lungs and is located within the radiation field. Characteristic imaging features include multiple alveolar opacities and diffuse ground-glass shadows. Letrozole may induce iatrogenic organizing pneumonia. Materials and methods: we report the case of a 76-year-old female who underwent conservative treatment for an invasive ductal carcinoma of the left breast. Hypofractionated radiotherapy was delivered with a total dose of 42.5 Gy in 16 sessions of 2.65 Gy using a three-dimensional technique. After the radiotherapy ended letrozole was indicated. Results: Several weeks after the radiotherapy ended and letrozole was introduced, she described a flu-like syndrome. Samples were negative, and there was no improvement after four courses of antibiotics. Imaging suggested bronchiolitis obliterans organizing pneumonia. Her symptomatology lessened after the letrozole was discontinued, and 11 months after radiotherapy finished, her imaging results were clear. Conclusion: Physicians must consider bronchiolitis obliterans organizing pneumonia. Cases may increase with hypofractionated radiation treatment and new drugs. Letrozole may potentiate the risk. Dosimetry may be adapted to the lung and subpleural areas for patients with risk factors and taking adjuvant or concurrent drugs with potential pneumotoxicity.