p16 expression in colorectal adenocarcinoma: marker of aggressiveness and morphological types

Aim: The aim of the present study was to investigate the clinicopathological roles of p16 expression in a large cohort of patients with colorectal adenocarcinoma with tight methodology and close follow-up. Methods: p16 protein expression was investigated in 194 patients (102 men, 92 women) with colorectal adenocarcinomas by immunohistochemistry. The findings were correlated with their clinicopathological features. Results: p16 protein was detected in 80% (155 of 194) of patients with colorectal carcinoma. The p16 protein was more often detected in male patients with colorectal cancers (86% versus 73%, p = 0.03). p16 protein expression was more often seen in carcinomas in the rectum, sigmoid and descending colon compared with more proximal colon (90% versus 61%, p = 0.001). The p16 protein was more often detected in well or moderately differentiated colorectal adenocarcinoma than poorly differentiated colorectal adenocarcinoma (84% versus 63%, p = 0.009). The level of expression of p16 protein is related to the lymph nodal status (p = 0.004) and the TNM staging of the colorectal carcinoma (p = 0.008). Conclusion: p16 protein expression was common in colorectal adenocarcinomas. The expression correlated with gender of the patient, distal location, differentiation and staging of the tumour. The findings suggest that p16 plays an important role in cancer pathogenesis and has implications for improving the clinical management.