Correlation between COX-2 and APC Expression in Left Versus Right-sided Human Colon Cancer

Background: Because of clinicopathologic and genetic differences between left-sided colorectal cancer (LSCRC) and right-sided colon cancer (RSCC), cyclooxygenase-2(COX-2) and adenomatous polyposis coli (APC) expression may be of clinical relevance. Materials and Methods: Clinicopathologic information for 72 primary colon tumors, 44 left and 28 right, from 72 patients (34 F, 38 M) were analyzed. COX-2 and wild- type APC (W-APC) immunohistochemical expressions were determined for each case. The data were analyzed using the Chi-square test and exact binomial confidence intervals. Results: Overall, 31 out of 44 (70%) LSCRC were W-COX-2 positive vs. 13 out of 28 (46%) RSCC (p-value=0.042). When evaluated independently of the anatomic location, COX-2 expression showed a borderline statistical correlation with the lack of W-APC protein (p-value=0.054). When considering location of tumors, the inverse correlation between COX-2 and W-APC expression became statistically significant (p- value=0.024). Conclusion: We report a strong inverse correlation between COX-2 and W-APC expression, with COX-2 being more frequently as expressed in LSCRC. These data may be useful to stratify colorectal cancer patients into right- and left-sided and COX-2 expressor and non-expressor subsets, when evaluating COX-2 inhibitor and other targeted therapies in colon cancer.