This is just my personal experience. I have not researched it at all. I found the sauna at my Gym and the steam room to be wonderful in stretching and relaxing the neck scars from my neck dissection. The heat helped me do the physical therapy exercises (I went in the day time when it was empty so nobody was there except me doing my PT). I started one month after my ND and told my physical therapist and my doctors and nobody said not to. But if you are worried, it cannot hurt to ask your doctors or therapist. I would not overdo it, my sessions were short but they felt great to me. I also did the lymphoma massages recommended to me.
Charm