Early metastatic seeding in colorectal cancer
Colorectal cancer metastases are generally believed to arise from a primary cancer cell subpopulation that accumulates additional genomic alterations.
Because of these specific added-on features, these tumor cells eventually become able to spread and implant at distant sites. Nonetheless, a Stanford University-led research team has recently discovered that numerous colorectal cancer metastases may have invaded distant locations well before the primary tumor was sufficiently large in size to be clinically detected, meaning less than 0.01 cm 3 .
To attain this conclusion, the Stanford researchers analyzed exome sequencing data from 21 evaluable colorectal cancer patients with liver or brain metastases. They looked for both similarities and differences between primary tumor and metastatic cancer samples obtained from the same person. In a next step, the researchers created some kind of evolutionary tree for each patient. When carefully analyzing these evolutionary trees, the research group detected that in most patients, namely in 17 out of 21, the metastatic tumor started by just one single cell or a small genetically-similar group of cells that broke off the primary tumor at a very early development stage. These cells that initiated the distant metastases were much more related to their ancestors from the primary tumor than to their current relatives within the metastatic site.
According to Curtis, the publication’s principal author, not all colorectal tumors will metastasize. It is thus essential to apprehend the cellular processes that keep the cancer from spreading to other sites.
https://www.ncbi.nlm.nih.gov/pubmed/31209394
Reference: Hu Z, Ding J, Ma Z, Sun R, Seoane JA, Scott Shaffer J, Suarez CJ, Berghoff AS, Cremolini C, Falcone A, Loupakis F, Birner P, Preusser M, Lenz HJ, Curtis C. Quantitative evidence for early metastatic seeding in colorectal cancer. Nat Genet. 2019; 51: 1113-1122. doi: 10.1038/s41588-019- 0423-x. Epub 2019 Jun 17. Jun 17.