CEACAM5 and squamous cell carcinoma: The positive rate of CEA was significantly lower in squamous cell carcinomas than in adenocarcinomas (27.0% versus 58.5%, χ2 = 3.981, P < 0.001), while the positive rates of increased Cyfra21-1, SCCA as well as NSE were significantly higher in squamous cell carcinomas compared to adenocarcinomas (P < 0.001 for all comparisons).