Most cancers - about 70% according to people who study these things, such as
Dr Robert Buckman - have little to do with anything a person does or doesn't do. Certainly, if your uncle smokes or is morbidly obese or has a poor diet or spends lots of time in the sun without protection, that will raise the risk of developing certain types of cancers. But there are lots of cancers (and other diseases) that don't seem to have a direct causal relationship with lifestyle, at least not that's been discovered yet. Bone cancer is one. Brain cancer is another, as is pancreatic cancer and some forms of leukemia.
I don't imagine it's any different with the thought-belief-intention scenario. Simple fact is that we just don't know. So assigning blame or looking for a thought needle in the proverbial haystack probably isn't of much use.