I had a good friend die of colon cancer in April, about 14 months after the diagnosis. He had chemo, then surgery, then more chemo, and radiotherapy in the end. The chemo and surgery held it off for a bit (he was noticeably better after those first treatments), but it kept coming back. In the end the radiotherapy was really tough on him and may even have killed him but he was on the way out anyway.
He was just 40. Left behind a wife he'd married just 2 years earlier and a 1-year-old son. He blamed the disease on his diet, way too much red meat and rich food, but of course it's impossible to know if that was the true reason or not.