Compared with CT alone, both anti‐PD‐1 + CT and anti‐PD‐L1‐based treatment + CT did not prolong PFS (HR, 0.62; 95% CI: 0.37%–1.05%; p = 0.074; and HR, 0.52; 95% CI, 0.26%–1.05%; p = 0.068, respectively; Figure 2A), but improved OS in SCLC patients with LM (HR for OS, 0.67; 95% CI, 0.54%–0.82%; p < 0.001; and HR, 0.85; 95% CI, 0.74%–0.99%; p = 0.034, respectively; Figure 2B). Here, PDCD1 is linked to small cell lung carcinoma.