Would you give additional radiation for a positive margin after salvage hysterectomy for a patient with cervical cancer who had initial definitive chemoradiation with EBRT+T&R?

I would favor repeat surgery if that is an option as otherwise salvage rate very low.

If it can't be done, then assess for interstitial brachy.

Patients usually have radical hysterectomy, so repeating surgery is not an option for most cases. I may recommend vaginal cuff brachytherapy in this case.