What do you consider negative or close margins for tonsillar cancers?

To answer your first question about margin for HPV+ (I assume) tonsillar cancers, one would have to go with the definition on clinical trial. Currently the WashU trial as well as RTOG 1221/ECOG 3311 and the ADEPT trial uses the 3mm cutoff. So a free margin is defined as something>/=3mm. Anything <3m...

I won't use chemo for close margins for tonsilar cancers, particularly if it's HPV positive cancer.