CEACAM5 and CEACAM6 expression was assessed in 6 different lung cancers: 5 each of well, moderately and poorly differentiated adenocarcinoma, 5 each of well, moderately and poorly differentiated squamous carcinoma, 3 each of large cell and bronchioalveolar, and 2 each of large cell neuroendocrine and small cell cancer. This evidence concerns the gene CEACAM5 and squamous cell carcinoma.