Clinical characteristics of nivolumab-induced radiation recall pneumonitis in patients with non-small cell lung cancer: A multicenter real-world analysis of 669 patients.
88 Background: Immune checkpoint inhibitors can cause immune-related pneumonitis in lung cancer patients. Some of those patients with history of previous thoracic radiation therapy (TRT) are reported to show radiation recall pneumonitis (RRP) pattern. In this multicenter retrospective study, we analyzed the patient background and clinical characteristics of RRP. Methods: Medical records of non-small cell lung cancer patients, who received nivolumab between December 2015 and March 2017, were retrospectively reviewed. Incidence of pneumonitis, and incidence, risk factors and clinical characteristics of RRP were analyzed at 5 institutions. Person’s chi-square test (age, sex, smoking history, performance status at the start of nivolumab treatment, background lung disease, history of previous radiation pneumonitis, total dose, volume receiving more than 20Gy, 30Gy, mean lung dose of TRT, and duration after TRT) was conducted to identify potential risk factors of RRP. RRP was defined as fibrosis or consolidation occurring in the previous TRT field, and imaging analysis was conducted by two individual radiologists. Results: A total of 669 patients were evaluated, and the incidences of all-grade and ≥ grade 3 pneumonitis were 8.8% (59/669) and 6.2% (18/669), respectively. Incidence of RRP was 5.4% (14/257) among patients with history of previous TRT. There were no significant risk factors for RRP. Although we did not find significant difference between the severity of RRP pattern and other radiological patterns of pneumonitis, patients with RRP showed better outcome. All patients recovered from RRP without no exacerbation or death, compared to 9.3% of exacerbation or death in other patterns of pneumonitis. Conclusions: Incidence of RRP was 5.4% among patients with history of previous TRT, although there were no significant risk factors of RRP. Patients with RRP pattern showed relatively better outcome.