Major Protein of Carcinoembryonic Antigen Gene Family - CD66c, A Novel Marker in Colon Carcinoma.

Introduction: In view of rising trend of the incidence of colorectal carcinoma in the Indian population due to adoption of western lifestyles and behaviours, we investigated the expression of the new emerging stem cell biomarker, CD66c in colorectal carcinoma of Indian origin.

Aim: To study the expression of CD66c in human colorectal carcinoma and to correlate level of marker expression with tumour staging.

Materials And Methods: This hospital based prospective study was conducted on 26 colorectal carcinoma patients in the age group of 20 years to 70 years. Surgically resected tumour specimens along with adjacent normal tissue were collected taking necessary precautions, paraffin embedded sections were prepared and used for histological and immunohistochemical analysis of CD66c.

Statistical Analysis: Descriptive statistical measures like mean, standard deviation, percentage was applied. Other inferential statistical tests like Chi-square, Fisher's-exact test and one-way ANOVA was applied to find out the association of CD66c with different stages. The difference were interpreted as statistically significant when p <0.05.

Results: CD66c showed differential expression with membrane positivity in normal colorectal epithelial cells and cytoplasmic expression in tumour cells. There was significant correlation between CD66c expression and tumour site (p=0.02) with colon carcinoma showing positive expression compared to the rectal carcinoma. There was no significant correlation between CD66c staining and tumour stage (p=0.947). No significant relationship was observed between CD66c expression and other clinicopathologic variables studied such as sex (p=0.552), age (p=0.713) and tumour grade (p=0.263).

Conclusion: CD66c can be specifically used for colon carcinoma and may be a novel marker in colon carcinoma stem cell isolation. The quantification of CD66c can be further verified by flow cytometry and RT-PCR. Further studies can be carried out using CD66c alone or in combination with other markers to develop cancer stem cell directed therapy.