> "What people die of" seems like the sort of question the medical community should be quite good at answering.

Yes and no, I think.

Technically my dad died of asphyxia. His cancer had spread to his lungs, he'd gotten pneumonia and was in hospital on oxygen. The doctors were clear he wouldn't be going home in the months he potentially had left. So he asked to be disconnected from the oxygen and he died an hour later.

So did he really die of asphyxia? Was it pneumonia, or the cancer? Clearly they were contributing factors, but in the end it was his decision to stop the oxygen, so as such was it suicide?

To me it doesn't really matter. He's gone and I'm just glad he didn't have to hang on to the bitter end.