In patients who are HPV postive, and non-smokers who have a complete PET response to induction TPF at the primary site, would you still treat the primary site to full dose?

Descalating therapy in HPV+ H&N SCC is the subject of investigation in ongoing clinical trials. Some are investigating de-escalation through the systemic agent used concurrently with RT (cetuximab vs cisplatin), such as RTOG 1016. Others are looking into the reduction of RT dose based on response to induction chemotherapy, which pertains more to your specific question.

ECOG 1308 was presented at ASCO this past year which was a phase II trial that looked at patients with HPV+ SCC of the oropharynx that were treated with induction Paclitaxel, Cisplatin, and Cetuximab. Response to induction chemotherapy determined RT dose. 54 Gy if cCR or 69.3 Gy if <cCR. PFS @ 23 months was 84% and 2 yr OS of 95% in patients that received low dose RT (http://...

I agree with @Dr. First Last. After induction chemo, I would recommend treating the primary and initially involved lymph nodes to 70 Gy regardless of response to chemo. There are several on-going studies and prelim data evaluating the possibility of reducing dose after induction chemo, but this data is not yet definitive. Delineating target volumes after induction chemo is quite difficult, especially after a good or complete response to chemo. The current guidelines recommend treating the initial tumor volume.