Incidence of pneumonitis in Asian patients with small cell lung cancer: A systematic literature review and meta-analysis.

e20123 Background: Pneumonitis is a well-documented adverse event (AE) among those with lung cancer receiving immune checkpoint inhibitor or radiotherapy. While several recent studies, such as the PACIFIC study, have reported a higher rate of post-chemoradiation pneumonitis in Asian compared with non-Asian patients with non-small cell lung cancer, information in small cell lung cancer (SCLC) is limited. Understanding the unique susceptibility and risk of pneumonitis in Asian patients is crucial for optimizing therapeutic efficacy and safety in this population. The objective of this study was to quantify the incidence of pneumonitis in Asian patients with SCLC. Methods: A systematic literature review and meta-analysis of clinical trials was conducted in accordance with PRISMA guidelines. English, Chinese, Japanese, and Korean literature databases were searched from 1/1/2014-8/2/2023. Clinical trials of lung cancer patients were included if conducted only in East or Southeast Asian countries, or if their results were stratified by these regions. Random-effects models were used to pool the incidence of all-grade (grade 1-5), grade 1-2, and grade 3-5 pneumonitis (including radiation pneumonitis) across the study arms. Meta-regression was also performed to evaluate the impact of radiotherapy doses on pneumonitis incidence. Results: Among 4,126 records identified from the search, 16 clinical trials with 2,118 SCLC patients were included in the meta-analysis. Regardless of treatment, the pooled incidence of all-grade, grade 1-2, and grade 3-5 pneumonitis in Asian patients was 12.21% [95% confidence interval (CI): 4.77-27.85], 7.64% [95% CI: 2.48-21.23], and 2.43% [95% CI: 1.47-3.97], respectively. Among patients who received radiation-containing treatments, the pooled incidence of all-grade, grade 1-2, and grade 3-5 pneumonitis was 42.49% [95% CI: 27.66-58.81], 23.58% [95% CI: 8.96-49.19], and 3.49% [95% CI: 2.07-5.82], respectively. For patients with limited-stage SCLC who received concurrent chemoradiation, the pooled incidence of all-grade, grade 1-2, and grade 3-5 pneumonitis was 50.61% [95% CI: 35.84-65.28], 29.81% [95% CI: 9.92-62.08], and 2.79% [95% CI:1.39-5.50], respectively. Higher radiation dose was associated with higher incidence of grade 1-2 pneumonitis, but not all-grade or grade 3-5 pneumonitis. Conclusions: This study quantifies the background risk of pneumonitis among Asian patients receiving any treatment for SCLC. When receiving radiation-containing treatments, incidence of grade 1-2 pneumonitis in Asian patients increases markedly, compared to no radiation. Radiotherapy dose is positively associated with grade 1-2 pneumonitis incidence but does not impact all-grade or grade 3-5 pneumonitis. Results from this study help to contextualize the safety data from SCLC trials combining other therapies with radiation.