Oropharynx-directed ipsilateral irradiation for p16-positive squamous cell carcinoma involving the cervical lymph nodes of unknown primary origin.

BACKGROUND: The purpose of this study was to present our findings on the use of limited-field, oropharynx-directed ipsilateral irradiation for p16-positive squamous cell carcinoma of unknown primary origin.

METHODS: Between April 2011 and January 2016, 25 patients with a histological diagnosis of p16-positive squamous cell carcinoma were selectively irradiated to the ipsilateral oropharynx and cervical neck for tumors of unknown primary origin. The dose to the oropharynx ranged from 54-60 Gy (median 60 Gy) in 30-33 fractions. Concurrent cisplatin-based chemotherapy was administered to 8 patients (32%).

RESULTS: The actuarial 2-year estimates of locoregional control, progression-free survival, and overall survival were 91%, 87%, and 92%, respectively. One patient failed in the contralateral neck. There was no grade 3 + toxicity in either the acute or late setting.

CONCLUSION: Oropharynx-directed, ipsilateral radiation results in disease control that compares favorably with historical controls treated by comprehensive mucosal and bilateral neck radiation.