The profits for a drug to cure every kind of cancer would be astronomical. You seem to have the assumption that when cancer is killed it cannot return. But, it can. Mutations happen often and because of this, cancer would happen often. Cancer kills people. You do not want your customers to die. It would be more profitable to release a cure and have people take it whenever cancer is found because it is certain to return.

You mentioned that changing your lifestyle has made you healthier, but that has been mentioned to me by my doctor every time I visit! Eat healthy, get plenty of rest, and exercise. We have heard this many times before. This is not some magical secret to a healthy life. Many people simply do not possess the willpower to do it. There are companies that profit from unhealthy choices because our bodies crave those unhealthy choices, but it does not mean there is some conspiracy by scientists to prevent drugs from reaching the market that can cure cancer.

The cure would be more profitable because over a long enough time line, cancer returns. People that get cancer are often predisposed to getting it in the first place.