I believe not just cancer but all other diseases. In this case of cancer I would same some people are responsible some are not. For example I grew up in a dusty area when cars pass by the dust get in the house. So we inhale and eat this dust unknowingly so if by accident I caught cancer I'm not responsible for catching it. Unlike a person who smoking willingy.
Another example would be breast cancer, some women just see a lump in their breast, goes to the doctor and he/she says it's cancer. Did she invite a lump? No, but she got it any way.