Cancer’s Darwinian dilemma: an evolutionary tale in three actsBMJ 2015; 351 doi: https://doi.org/10.1136/bmj.h6581 (Published 15 December 2015) Cite this as: BMJ 2015;351:h6581
- Mel Greaves, director
- 1Centre for Evolution and Cancer, Institute of Cancer Research, Sutton, UK
“Nothing in biology makes sense except in the light of evolution”
Theodosius Dobzhansky, 1973
There are upwards of 10 million new cancer cases a year in the world. One in three of us can expect that unwelcome diagnosis, and around one in four will succumb to metastatic, drug resistant disease. The big questions are, why are humans so vulnerable to cancer? what exactly is cancer as a biological process? and why is drug resistance the norm for advanced disease? Evolutionary biology has something to say about each of these grand challenges.
Act 1. Why are we so vulnerable?
Species in almost all animal phyla, including within the invertebrates, can develop cancer.1 But there is one stand out group here, and it’s Homo sapiens. Our cancer rates are through the roof. It’s sometimes posited that this reflects the inevitable price of surviving into old age. Cancer risk is certainly age associated, and cancer in other mammals (such as horses) increases with age. But it’s not driven by the degenerative effect of ageing. This is evident from the highly variable incidences of the major cancers over time and in different geographical settings. So what is it? Is it industrial pollution, electricity pylons, your parents’ genes, divine retribution, or just “bad …