Chapter 7 Chromosomal copy number aberrations in colorectal metastases resemble their primary counterparts and differences are typically non - recurrent

The metastatic process is complex and remains a major obstacle in the management of colorectal cancer. To gain a better insight into the pathology of metastasis, we investigated genomic aberrations in a large cohort of matched colorectal cancer primaries and distant metastases from various sites by high resolution array comparative genomic hybridization. In total, 62 primary colorectal cancers, and 68 matched metastases (22 liver, 11 lung, 12 ovary, 12 omentum, and 11 distant lymph nodes) were analyzed. Public datasets were used for validation purposes. Metastases resemble their matched primary tumors in the majority of the patients. This validates the signi!cant overlap in chromosomal aberrations between primary tumors and corresponding metastases observed previously. We observed 15 statistically signi!cant different regions between the primary tumors and their matched metastases, of which only one recurrent event in metastases was observed. This speci!c recurrent event includes two chromosomal regions, 6q21 and 8q24.21 encompassing the MYC oncogene, that co-ampli!ed in three metastases of two patients (3.2%) and was not seen in the primary tumors. Fluorescence in situ hybridization was used to technically con!rm this observation. This co-ampli!cation could not be observed in any of the other datasets of primary or metastatic tumors. We conclude, based on detailed analysis and large independent datasets, that chromosomal copy number aberrations in colorectal metastases resemble their primary counterparts, and differences are typically non-recurrent.