What are the chances of me getting cancer?

As a cancer patient, my understanding is that if you've had relatives with certain cancers then you are at increased risk for it. It's not a sure thing, just something to be very watchful for. As for men? I'm a man and there was no history of cancer in my ancestors yet here I am with it. There is so much that is still unknown. What happened with your grandmother is very sad but that was then and the science is a lot better now. You make sure you are routinely screened for the cancer that is worrying you so and even if it does develop, it will be caught very early when it's almost a guarantee you will survive it. Don't waste your young, wonderful years worrying about something that will probably never occur. Get out there and enjoy your life and quit stressing!