I understand we want to contribute cancer to something someone directly did, but that isn't always the case. Cancer sometimes just happens.
https://www.cancer.org/content/dam/cancer-org/research/cance...
Yeah, cancer can "just happen" to anyone, but there are undeniable factors that can significantly increase your chances of getting it, such as poor diet or being overweight.
You might not like it, but those are the facts.
That said, I'll also put out there that I think a a lot of people are overly dismissive of "Supersize Me" by pointing to Spurlock's alcoholism, completely ignoring how bad fast food is, on every level.