James DeGregori in Stat News:
Just about everything we know that decreases the risk of developing cancer — exercise, healthful eating, not smoking, and the like — is associated with healthier tissues, which favor normal cell types.
Unfortunately, youthful, healthy tissues aren’t maintained forever. Aging and various behaviors or external insults, think cigarette smoking or radiation, modify tissues, and rarely for the better. Such changes favor cells with genetic changes that foster their ability to adapt to the altered environment. Damaged or degraded tissue favors undesirable (at least from our point of view) cell types — deviant cells that no longer play by the rules.
My lab has shown that the combination of changes in tissue environments and cells’ evolutionary responses to them can promote cancer.
This evolution-based theory doesn’t apply only to the origin of cancer. It is also relevant to treatment: Anti-cancer therapies that damage healthy tissues, like chemotherapy and radiation therapy, can promote the emergence of more aggressive cancer cells and even new types of cancer.