Dude, what does this have to do with Love and Sex? Just asking. But whatever, scratching a mole off your arm is not going to give you cancer. Don't worry about it. It will most likely grow back, and when it does, if it bothers you, go to a dermatologist and have it removed.
naa scratching a mole off wont give you cancer at all. if they turn funny colour's and stuff it might be a sign of something. if you are worried go and see a doctor!!!!