In the USA in the past cancer was covered up and viewed as a family shame. You did not want others to know. In Japan this has existed until more recently and I think is still there to an extent.
Cancer used to be much rarer in America. That is was unusual 70-80 years ago was part of the reason families would cover it up. Plus is was a spooky hard to understand ailment. It was viewed as being a reflection of your bad character etc etc. I am simply stating how it used to be.
Yep. There is now, as I said, some new avenues of research and there are generally warnings against too firm conclusions. But if heavy stress may induce onset of cancer (and other diseases, for that matter), you may posit that constant raging hatred may be a stress generator.