I had tried to research that topic over the years with no convincing evidence one way or the other, to my mind.
Fitness, diet, training load, recovery, and how hard one rides all come into play. You really have to study what is going on at the mitochondria. Way too much to discuss on a forum. Some energy pathways produce more ROS than others. Whether any supplements like NAD+ or ubuquinol help is well...not well known despite supplement companies like trueniagen's claim. Who knows.
Personally, I think it is possible to overdo it but a couple of SR series and a 1200K with adequate rest isn't too much for my way of thinking.
Taking ibuprofen is a sure way to slow healing. I think endurance exercise can actually make one heal quicker. I've had some surgeries and also some (10) broken bones and the Docs were astonished how quickly I healed and I would say it is because endurance exercise has my body fixing itself all the time and thus, it is good at it. I doubt my cancer risk is higher.