Assume you’re life-lusted and are willing to abandon every moral you have just to live. Paying for cancer treatment is also worth prison time to you.
Also assume you’ve exhausted all ethical fundraising options, i.e. GoFundMe, loans, etc. and that insurance won’t cover treatment for whatever reason.
Touristic visas only last 90 days. And usually the hospitals will only provide emergency care to tourists. They might be willing to stretch that definition a lot but not to the point of doing things that need to be regularly scheduled.