RESUMO
In order to establish the most appropriate protocol of adjuvant chemotherapy for colorectal cancers, several cooperative studies have been undertaken by the Kinki Cooperative Study Group of Chemotherapy for Colorectal Carcinoma (KCSGCCC). In the No. 3 protocol of KCSGCCC, several cancer-associated molecular markers were analyzed to investigate a possible correlation with chemosensitivity and/or patient's prognosis. Here, we report the preliminary results of the analysis of microsatellite instability (MSI) and p53 LOH in 559 cases of Stage II, III colorectal cancer. The MSI was detected in 51 cases (9%) and was shown to have a significant correlation with right-sided localization and histology (poorly differentiated, mucinous). p53 LOH was positive in 225 cases (40%) and was shown to have a significant correlation with left-sided localization and histology (well to moderately differentiated). These results might support the concept of 2 distinct pathways of colorectal carcinogenesis, e.g., RER pathway and LOH pathway.
