Friend of mine told me he thinks his previous marriage gave him cancer

Definitely stress kills more people than almost anything else and because your relationships especially marriage is so close intimate and intense it can easily cause that same with having terrible parents etc it's sad but very true no doubt

There have been studies that have proven as much. Prolonged stress and trauma, even negative feelings, can lead to body illness. We forget our brains and brain chemicals are connected with the rest of us.

I don't buy that.

Negative energy can do that.