With some situations, the risk/benefit has to be considered. Re: Treating cancer, every case is different. An aggressive cancer requires more-aggressive treatment, & that treatment can (and has) killed patients. You may recall when Mike Connors was diagnosed with Leukemia at age 91, there wasn't anything that could be done for him. He died soon after diagnosis. (I don't know if he was treated or not).Unfortunately they do, my aunt in her late 80's was refused to do gallbladder surgery because of her age. A friends husband had heart issues, they told her to take him home to die. I'm hearing they won't even treat cancer? It's the insurance companies deciding this.
When my dad was diagnosed with prostate cancer, he was 74. At first, I was surprised when his oncologist said "We're not going to treat him because he will probably outlive it & the treatment will ruin the quality of his life with no benefit." He died at 88 from a fall. In that case they were right.