Incidence, risk factors, and CT characteristics of radiation recall pneumonitis induced by immune checkpoint inhibitor in lung cancer

Background and purpose Radiation recall pneumonitis (RRP) is a delayed radiation-induced lung toxicity triggered by systemic agents, typically anticancer drugs. Immune checkpoint inhibitors (ICIs) have recently been identified as potential causal agents of RRP but its real incidence risk factors remain unknown. Materials methods Medical records CTs patients treated with programmed death 1 (PD-1) or ligand (PD-L1) for advanced cancer between 2014 2019 at our tertiary center, who had previous history irradiation were retrospectively analyzed. We CT modifications occurring in the field >6 months after conventionally fractionated radiotherapy completion >1 year stereotactic body radiation therapy. Clinical dosimetric data analyzed to identify RRP. Results Among 348 ICIs, from 80 eligible (median age, 69 years [interquartile range, 11]; 45 men). Fifteen (18.8%) presented Median time end was 450 days (range, 231–1859). No factor significantly associated ICI-related 33.3% cases (p = 0.0021), developing either concomitantly Incidence grade ≥ 3 population 13.3 %. Conclusion demonstrated high previously irradiated ICIs cancer. no RRP, an association noted pneumonitis.