Steroid treatment increases the recurrence of radiation-induced organizing pneumonia after breast-conserving therapy

Radiation-induced organizing pneumonia (RIOP) is an important complication of postoperative radiotherapy for breast cancer. Unfortunately, conventional corticosteroid therapy is frequently associated with relapses. The aim of this retrospective study was to evaluate the outcomes of steroid treatment in patients with RIOP. In total, 26 patients diagnosed with RIOP from among 2404 women who received radiotherapy after breast-conserving surgery for breast cancer were included and classified into steroid (n = 7) and nonsteroid (n = 19) groups. Serum, sputum, and bronchoalveolar lavage composition; subjective symptoms (cough, fever, and dyspnea); migratory progression; and RIOP relapse were compared between the groups. Treatment type did not affect the duration of the subjective symptoms, which was 1.6 and 1.7 months for the steroid and nonsteroid groups, respectively. In contrast, RIOP relapse and new pulmonary lesions developed in five patients in the steroid group and only three patients in the nonsteroid group (P = 0.014). By assessing RIOP duration as the time to resolution of symptoms and discontinuation of therapy, the median duration of RIOP was significantly longer in the steroid (17.1 months) than that in the nonsteroid group (2.3 months, P = 0.005), primarily because of frequent relapses. After remission, persistent pulmonary dysfunction did not occur in the nonsteroid group. This single-center retrospective study demonstrates that steroid therapy results in frequent relapses and significantly prolongs RIOP duration. Corticosteroid treatment is considered a critical factor in RIOP recurrence.