Correlation of COX- 2 Expression in Colorectal Carcinoma with Clinicopathological Features

Colorectal carcinoma is the most common neoplasm of the gastrointestinal tract. COX-2 expression is upregulated in colorectal carcinoma. Therefore its assessment would identify patients amenable to adjuvant anticyclooxygenase therapy. We studied COX-2 immunoexpression in colorectal adenocarcinoma and correlated it with clinicopathological features as age, gender, tumor location, tumor size, degree of differentiation, and TNM stage.

Sixty-five consecutive cases of colorectal adenocarcinoma were retrieved from the records of the Pathology Department of a tertiary care hospital. The tumors were categorized as low positive and high positive based on their total COX-2 scores, which is the sum of proportion and intensity scores of immunostaining, and were correlated with clinicopathological features. Statistical analysis was done using the Chi-square test and Kendall's Tau-b correlation method.

COX-2 was expressed in 86.2% of cases including 90% of left colonic carcinomas and 77.3% of right colonic carcinomas. Lymph node metastasis was present in 22.2%, 25% and 47.75% of COX-2 negative, low positive and high positive tumors respectively. High positive COX-2 cases constituted 33.3% of stage I, 58.8% of stage II, 80% of stage III and 100% of stage IV tumors. About 56.6% of well differentiated, 66.6% of moderately differentiated and 100% of poorly differentiated carcinomas showed high COX-2 expression. The COX-2 overexpression was associated with advancing depth of invasion (p=0.021), stage of tumor (p=0.05), more frequent lymph node metastasis and decreasing degree of differentiation.

The association of COX-2 overexpression with increasing stage and depth of invasion may justify the use of COX-2 inhibitors as an adjuvant to chemo and radiotherapy.