A very interesting and timely article on tumor heterogeneity was published in the New England Journal of Medicine today. Gerlinger and colleagues from the UK used next-generation sequencing to look for heterogeneity across various regions of renal tumors and metastases in four patients. They report that indeed there is a great deal of heterogeneity within individual tumor nodules–in fact, most of the many alterations to the tumor genome were not shared across all nodules. Further, analysis of the pattern of mutations revealed branching evolution of the primary tumor and its metastases, rather than a linear pattern of progression of the cancers.
A couple of important conclusions suggested by this work:
- Single biopsies of the primary tumor may give you a very misleading understanding of the cancer.
- Cancer stem cells may not be what we thought they were, if they exist.
- Confirms the adaptability of cancers by demonstrating convergent evolution of functional gene alterations.
None of what was reported is inconsistent with evidence from previous decades of cancer research. It was work that really needed to be done and I’m happy it appears to have been completed in a careful, thoughtful way.