Although not from the cancer itself. He died of an opioid overdose. He was prescribed pain killers for cancer-related pain, and got hooked. His doctors stopped prescribing, so he found it elsewhere, and got a bad batch with fentanyl. (He was a VC living in SF, well to do, he had all the treatment money could buy, but cancer ended up not being what killed him)
I know this isn’t what you’re looking for, but be sure to not ignore other parts of his health. Addiction and other disorders are common among people with terminal or not-so-great prognosis.
The most you can do is to be a great friend.