Research progress on genetic heterogeneity between primary and paired metastatic colorectal cancer

Colorectal cancer (CRC) is one of the leading causes of cancer deaths in China. A standard practice in treating metastatic CRC (mCRC) is to predict benefits of the anti-EGFR monoclonal antibody treatment based on the somatic mutation spectrum. Because metastatic samples are difficult to obtain clinically, primary tumors are normally used instead. However, due to the genetic heterogeneity between primary and paired metastatic tumors, primary site biopsy always underrepresents the mutational landscape of metastatic sites. Currently, the extent of genetic heterogeneity between primary and paired mCRC is still under debate. Here, we review comparative studies of primary and matched mCRC and discuss the underlying causes and potential strategies.