How do you manage pT1-2N0 p16+ tonsil cancer treated with TORS and ipsilateral negative neck dissection but with positive margin?

This would be a very unusual situation, especially if the Q is in reference to the palatine tonsil. A well trained Robotic surgeon generally would not have any problems with performing a Radical tonsillectomy for an early stage tonsil primary. The superior constrictor and the pillars (ant+post) form the anatomical boundaries for a palatine tonsil. Thus, a plane enveloping the tonsil is readily developed and early stage tumors are readily cleared. However, the medial face of the tonsil is open to the pharyngeal lumen. Here, the tumor has access to spread via the GP sulcus onto the tongue base, and it is possible to get a tight margin. If this were the situation, I would ask the surgeon to re-operate and get a wider clearance medially. We sho...

I completely agree with @Dr. First Last's comments. In the hands of a well-trained head and neck surgeon, the chance of a positive margin in a T1-2 tonsil/ base of tongue ca would be very unusual. Even if this were to happen, a re-excision should be attempted. If these T1-2 opx cancers are completely resected locally and N0 on neck dissection, they can then be observed and not subjected to any further therapy.

If there was a positive margin and no possibility of re-excision, I would treat with RT alone. I would include the ipsilateral neck if the tonsil was well lateralized. In case of extension to the base of tongue or lesions going close to the uvula, I would treat bilateral necks. There is always a risk of nodal failure even in N0 necks....

We see this on occasion from surgeons in the community and I do not consider it a true oncologic surgery, and would also treat with radiation therapy alone if re-excision from a well trained surgeon is not possible. I just consider it a big biopsy and do not see a role for concurrent radiation. I would treat the primary site to 66 Gy in 30-33 fractions and include the ipsi level II-IV, RP nodes to low-intermediate dose.