<i>Pneumocystis jirovecii</i> pneumonia during adjuvant chemotherapy of breast cancer: a hidden complication of the prophylactic corticosteroids?

We report three cases of Pneumocystis jirovecii pneumonia (PJP) in patients with early-stage breast cancer undergoing (neo) adjuvant chemotherapy.All cases were associated with cumulative prophylactic corticosteroid exposure exceeding thresholds for PJP prevention thresholds accompanied by significant lymphocytopenia.Disease severity varied, with one patient requiring invasive mechanical ventilation.Despite this, all cases achieved favorable clinical and oncological outcomes.These cases underscore the importance of increased vigilance, optimization of corticosteroid dosing, and the implementation of prophylactic measures to reduce infection risk.In response, our institutional protocols were updated to lower corticosteroid prophylactic doses in the chemotherapy regimens.