Cure Cancer

I just found out that i may have skin cancer, if I don’t get any treatment for it what will happen?

I have always read stories about people loosing weight when they have cancer. I know there are certain kinds that can make people weigh less than 100 lbs, but what causes the weight lose? Is it the chemo and medicine, or if you go untreated, will the cancer cause this on it’s own?

Also any other statistics about breat cancer are a great help. I need this info for a school project. Thanks!

For example, a cancer that you always need a lot of tests and treatments for, so you have to stay in the hospital, but you’re not on bed rest, so you can still walk around and everything?
Does that exist?
I’m writing a story where the main character has this type of cancer, so I need to do some research but can’t find anything like this. If there’s nothing, I could just make up something… But I’d like to keep it as realistic-fictional as possible, please.
Thanks!

I was wondering this, because one of my friends thinks she has breast cancer, and I thought that thirteen was a very young age at which to develop breast cancer.