Clinical and molecular biologic characteristics of early-onset versus late-onset colorectal carcinoma in Filipinos.

A case-control study of Filipino patients who underwent surgical resection for colorectal cancer (CRC) during a 1-year period was undertaken. Thirty-five patients under age 40 years were identified. Paraffin blocks of these and 35 randomly selected patients over age 40 underwent histologic and immunohistochemical evaluation. Markers chosen for evaluation included the apoptosis-associated gene products (p53 and bcl-2), a tumor proliferation activity-related factor (Ki-67), and the markers (MLH1 and MSH2) of DNA microsatellite instability (MSI). Results were correlated with age and the stage and location of the tumor. The average age of the early-onset group was 30.7 years compared to the late-onset group at 67.0 years; and the male/female ratio was equivalent. The younger patients had a significantly higher Dukes' stage, the tumors were more poorly differentiated, and they were more frequently of the mucinous and signet ring cell histopathologic type. Expression of p53 was higher in the younger patients ( p < 0.001) and was independent of the degree of differentiation or the stage of the tumor. No differences of expression were noted for the other markers measured. The increased frequency of CRC in Filipino patients less than 40 years of age offers a unique opportunity to gain a better understanding of carcinogenesis, which might be exploited during diagnosis and management. The differences noted between the early- and late-onset CRC are provocative and provide an impetus for increased screening in Filipinos.