From Medical Xpress:
Why are older people at higher risk for developing cancer? Prevailing opinion holds that, over time, your body's cells accumulate DNA damage and that eventually this damage catches up with the body in a way that causes cancer. A University of Colorado Cancer Center study published today in the journal Aging shows that this prevailing opinion is incomplete. In addition to DNA damage, cancer depends on the slow degradation of tissue that surrounds cancer cells, something that naturally comes with aging.
“It's really all about natural selection and survival of the fittest,” says James DeGregori, PhD, investigator at the CU Cancer Center, professor of Biochemistry and Molecular Genetics at the CU School of Medicine, and the paper's senior author. “When you're young, healthy cells are optimized to the surrounding tissue – they're the 'fittest',” DeGregori says. “At that point, any mutation that affects function makes a cell less fit, so cells with mutations, even cancer-causing mutations, are out-competed by the young, fit, healthy cells. But when the tissue landscape changes with aging, healthy cells may no longer be optimized to their surroundings. In this aged landscape, mutations may actually make certain cells better, allowing them to out-compete the normal cells and form tumors. That's why older people get cancer.”