[Alternations of p53 gene, microsatellite instability and proliferation associated antigen Ki-67 in the synchronous...

To evaluate the malignant potential of synchronous multiple colorectal cancers, we studied clinicopathologically 31 synchronous multiple colorectal cancers resected at our hospital. We also compared the p53 gene mutation rate, replication error (RER) rate, and Ki-67 antigen positivity rate between these cancers and 90 sporadic colorectal cancers. There was no significant difference in lymphoid and venous invasion, hepatic metastasis, or stage of colon cancer between the two types of cancers. The p53 gene mutation rate was lower in synchronous multiple colorectal cancers (p < 0.05). The RER rate and positivity rate for Ki-67 antigen was significantly higher in these cancers (p < 0.05). These results suggest that some synchronous multiple colorectal cancers result from carcinogenesis in which RER genes are involved, as HNPCC does. In the patients with synchronous multiple colorectal cancers, it is clinically important to follow them carefully focusing on multiple metachronous colorectal cancers and multiple organ cancers.