Bronchiolitis Obliterans Organizing Pneumonia After Breast Radiation Therapy

Presented here is a case report of a 77-year-old woman affected by rheumatoid arthritis who underwent breast-conserving surgery followed by radiation therapy (RT) for left-breast cancer and developed bronchiolitis obliterans organizing pneumonia (BOOP) after RT and during a COVID-19 vaccination campaign. BOOP incidence is an uncommon morbidity after breast RT (1.2%-2.9%); however, specific predisposing factors can play a role. In this patient, both rheumatoid arthritis and the vaccine may have predisposed her to an increased risk of organizing pneumonia, probably by triggering a proinflammatory cascade. Our report highlights the importance of factors that influence the occurrence of uncommon radiation-induced morbidities, such as BOOP, in specific subsets of patients. Further studies are necessary to evaluate factors increasing radiation sensitivity.