expression of cyclin d1 and p16 in esophageal squamous cell carcinoma

background: esophageal squamous cell carcinoma (escc) is one of the lethal cancers with a high incidence rate in asia. many genes including cyclin d1 and p16 play important role in its carcinogenesis. we aimed to analyze the expressions of cyclin d1 and p16 with the various clinicopathological characteristics of escc.   method: we examined 30 biopsy samples of escc for cyclin d1 and p16 protein expressions using immunohistochemistry. immunointensity was classified as no immunostaining (-), weakly immunostaining (+), weak immunostaining (++) and strongly positive immunostaining (+++).   results: out of the 30 cases, positive expression of cyclin d1 was detected in 26 cases (86.7%). the percentage of tumors with invasion to the adventitia (88.2%), lymph node metastasis (87.5%), and tumors which were poorly differentiated (92.9%) were higher in  cyclin d1 positive tumors than in the cyclin d1 negative tumors. however no significant association was found between cyclin d1 expression and the different clinicopathological parameters.there were 22 cases of escc (73.3 %) which showed negativity for p16. the percentage of tumors with invasion to the adventitia (82.4%) and poorly differentiated tumors (92.9%) were higher in the p16 negative tumors than in the p16 positive tumors. there was significant association between the histological grade and p16 expression ( p =0.012). however, there were no significant association with regard to site, size and lymph node status of the tumors and p16 expression.   conclusion: the study shows that alterations of cyclin d1 and p16 play an important role in escc. loss of p16 expression was associated with poor differentiation.