CT findings of lung injury during breast cancer treatment

While breast cancer treatment outcomes have improved significantly through multidisciplinary approaches including surgery, chemotherapy, and radiation therapy, the incidence of non-neoplastic pulmonary complications has also increased. Accurate interpretation of chest imaging is essential for managing these adverse events. This review outlines the major radiological findings of pulmonary injury during breast cancer treatment, focusing on two primary categories: drug-associated interstitial lung disease (DILD) and radiotherapy-associated lung injury (RLI). Regarding DILD, its clinical features, risk factors, differential diagnosis, and diverse patterns on high-resolution CT (HRCT) are described. The lung injury characteristics associated with specific drugs used in breast cancer treatment are also examined, placing particular emphasis on clinically important agents like trastuzumab deruxtecan. Regarding RLI, the pathophysiology (including acute radiation pneumonitis and chronic radiation fibrosis), relevant risk factors, and typical CT findings localized to the radiation field are discussed. Atypical manifestations are also addressed, such as radiation-induced organizing pneumonia (OP) outside the radiation field and the unique phenomenon of radiation recall pneumonitis. These complications can present with symptoms and imaging findings that mimic one another as well as other conditions, such as infections and lymphangitic carcinomatosis. This review aims to facilitate the timely and accurate differential diagnosis of pulmonary complications in breast cancer patients, thereby guiding appropriate therapeutic strategies and enhancing patient safety.