Genomic profile of colon cancer metastases.

Background: In colon cancer, the occurrence of metastases is associated with microsatellite stability. As metastatic cells derive from a clonal expansion of primary tumor cells, specific genomic alterations are expected in addition to the common genomic profile. Patients and Methods: Genome-wide allelotyping was performed on 75 liver metastases samples from sporadic colon cancer. Results: No microsatellite instability was observed. Allelic loss on 5q in metastases was significantly different from that of non metastatic primary tumors (16/58 vs. 43/75, p=0.0008). Four additional chromosomes, 4, 7, 8 and 19, were more frequently lost in liver metastases, but statistical significance was reached only for 19q (14/63 versus 2/68 in primary tumors; p=0.033 after Dunn-Sidak adjustment). Conclusion: This study, confirms that liver metastasis is rather restricted to patients with microsatellite stable colon cancer and these retain the 5q arm with high frequency. In addition, it suggests that loss of 19q may be critical for one of the steps involved in the development of liver metastases.