A genetic variant that increases the risk of testicular cancer may be favored by evolution because it helps protect those with fair skin from the sun’s damaging ultraviolet rays, according to a new study. The finding could account for white men being more susceptible than black men to this type of cancer. It may also explain why testicular cancer is so readily treatable.
Gareth Bond, a molecular biologist at the Ludwig Institute for Cancer Research in Oxford, U.K., and colleagues hit upon the unexpected tradeoff while studying inherited genes that influence cancer risk. They were especially interested in a gene known as p53, which is mutated in more than half of all cancers. The protein produced by this gene is a key defense for the cell—acting on a wide array of other genes to protect against many types of stress, including DNA damage and oxygen deprivation. It also protects against cancer, telling badly damaged cells to commit suicide. Mutations in p53, or in other genes with which it acts, prevent this order from being received, and damaged cells continue to reproduce, forming tumors.
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