Among the 142 patients, PD-L1 expression was more commonly observed in females than in males (32%, 16/50 vs. 13%, 12/92, p = 0.009), in central type than in peripheral type SCLC (26%, 26/100 vs. 4.8%, 2/42, p = 0.003), and in TTF-1 positive than in negative cases (23.8%, 25/105 vs. 8.1%, 3/37, p = 0.039). This evidence concerns the gene TTF1 and small cell lung carcinoma.