Chewing on a cigar. Harmful?

A co-worker of mine had a mild stroke. This convinced him to quit his 2 pack a day cig habit that he had for over 30 years! That was 3 years ago, and believe it or not, the son of a gun actually hasn’t had a single grit!
But what he does do is chew on a cigar (it’s not lighted).
He never smokes them, just chews on the end. Anyone know of any data that this in itself can be unhealthy?

Yes. I don’t want to do the legwork for you, but chewing on that stogie could give him a good case of mouth, throat, stomach or colon cancer eventually. But he knows that. His doctor has told him. But if he is in his 50s and has quit smoking, he has more going for him than not.

mildly dangerous, especialy if he keeps it in one spot a lot. But NOWHERE near as dangerous as smoking. Compare it to jumping off a 1 story bldg, to a 5 story bldg. If this is what he needs to stop smoking cigs, then let him be.