Hello John, these happen often enough for us to have heard about them. (I did not personally have one). The best description in lay terms is that the healing process needs to find a path for fluid to drain out. Because the normal flow of lymph has been disrupted by the treatments, the fistula forms. They can also be the result of infection. Over time they usually heal by themselves. I am not a medical expert, but it would seem to me that if it is still draining then surgery to close it would mean nature would try to open a path again.

Take care

Mark, 21 Year survivor, SCC right tonsil, 3 nodes positive, one with extra-capsular spread. I never asked what stage (would have scared me anyway) Right side tonsillectomy, radical neck dissection right side, maximum radiation to both sides, no chemo, no PEG, age 40 when diagnosed.