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.
Where I live police monitors those things. They will even check pawn shop inventory for jewellery reported as stolen and you have to show an ID to pawn anything. You would have to sell it to some random guys on the street which would be risky.
Sell it in another country or online.