Racial differences in the prognostic usefulness of MUC1 and MUC2 in colorectal adenocarcinomas

There is a need for new prognostic parameters that could add insights into the aggressiveness of tumors. Because the expression of two well-characterized mucin antigens, MUC1 and MUC2, in colorectal adenocarcinomas (CRCs) has been correlated with the aggressiveness of CRCs, we evaluated the prognostic value of the expression of MUC1 and MUC2 in CRCs collected from African-American and Caucasian patients. Expression of MUC1 and MUC2 was evaluated by immunohistochemistry in 166 archival CRC specimens collected from 58 African-American and 108 Caucasian patients that had been analyzed previously for nuclear accumulation of p53 (p53nac). Univariate Kaplan-Meier and multivariate Cox proportional hazards models were used to determine the prognostic significance of expression of MUC1 and MUC2 in these CRCs. MUC1 expression was more frequent in advanced stage CRCs, whereas MUC2 expression was higher in the mucinous type of CRCs. Although similar proportions of CRCs from African-Americans and Caucasians expressed MUC1 and MUC2, the MUC1 expression was found to be an indicator of high risk of death from CRC in Caucasians (hazard ratio, 2.03; P = 0.038) but not in African-Americans. Furthermore, Caucasians with CRCs exhibiting concomitant expression of MUC1 and p53nac demonstrated the lowest probability of overall survival (log rank test, P = 0.004). No prognostic value was found for MUC2 alone or in combination with p53nac in either group of patients. Expression of MUC1 in CRCs is a valuable indicator of poor prognosis in Caucasian patients. Additionally, combined evaluation of MUC1 and p53nac increases the ability to identify Caucasian patients with aggressive subtypes of CRC and may be useful in selecting or in developing novel therapeutic regimes.