While analyzing Bhattacharjee’s, Hou’s, and Garber’s datasets, we detected a significantly lower SP-D mRNA expression in lung adenocarcinoma, squamous cell carcinoma, large cell carcinoma, small cell carcinoma, and tumor carcinoid, compared to the normal lung tissue (Figure 1A, p < 0.05; Figure S1 in Supplementary Material, p < 0.05). This evidence concerns the gene SFTPD and squamous cell carcinoma.