This is not true.

It’s not about cancer, it’s about senescence. Mammals’ and many other animals’ only way to adapt to an ever changing enviroment, is: remix genes + mutations + epigenetic factors. And hope for the best.

In order for parents to not compete with their offspring for food or sex, they have to die. Which can simply be a limited lifespan by cells getting sloppy in their maintenance, or by choosing to starve yourself to death.

If you get injured badly, you have failed to survive. It is more energy and evolutionarily speaking to let you die, than expend energy on your recovery. Energy is limited in every enviroment. Depression and lethargy are interesting aspects to self-elimination (not suicide) as well.

Senesence is also why cancer is far more common in older people than in children. Our repair functions stop doing their job well as part of senescence. Increasing the chance and speeding up the development of tumors.

I mean. Artificially lowering the grades of female med students is civil war worthy.