Such questions have been asked many times on the forum. It's an understandable desire, but the short answer is no.
@HelensNepenthe and @nitrogen are the only ones I've seen give ideas about how to possibly get cancer.
But I think it's a romantic idea to want to get an incurable disease. You will suffer greatly and want to ctb to end the misery.
I think it's better to work through the guilt. Guilt is a message accompanied by negative feelings. Guilt usually says you are wrong for doing something for yourself, and it's usually invalid. It's kind of like being gaslighted by your own mind. Guilt messages usually come from childhood messages by social groups such as family and society. Guilt usually says someone else's needs, wants and suffering carry more weight than your own.
Shame, on the other hand, negates you as a person. It says things like, "You're not good enough," "How dare you?" and "Who do you think you are?"
Would you like to talk about the guilt here and try to work it out?