New Study
Ahhha, another new study. So many are contradictory so what do you do. In the case of tennis just keep playing if you already are since it can't hurt you. At least they haven't come up with a study to say it does. About the biggest risk is skin cancer and how you dress and whether you use sun screen can help limit that concern.
Getting a workout is the key element of the benefits of tennis so whatever you do try to find the time to get in your weekly or twice weekly workout.