Similarly, in other tumor types including MM, HNSCC, prostate cancer and mesothelioma, PD-1 inhibitors showed significant increase in grade 1-5 and grade 3-5 pneumonitis (RR, 5.69, 95% CI: 2.00-16.24, p < 0.001; RR, 4.05, 95% CI:1.04-15.78, p < 0.05, respectively) but no increase in the risk of pneumonia. This evidence concerns the gene PDCD1 and head and neck squamous cell carcinoma.