Our findings indicated that CD39 + CD8 + T cells were detected at similar frequencies in adenocarcinoma-related MPE (15.29 ± 2.14%) when compared to small cell lung cancer (12.40 ± 2.66%, P = 0.94) and squamous cancer (10.30 ± 1.73%, P = 0.86). This evidence concerns the gene CD8A and small cell lung carcinoma.