Long-term Locoregional Control With Unilateral Radiation for AJCC-7 T1-2N2b Tonsillar Cancer

Objectives: Unilateral radiation to cervical nodes has been used as a de-escalation strategy in well-lateralized tonsil cancers. The efficacy of this approach with multiple ipsilateral nodes is not established. The study hypothesis was that unilateral radiation for American Joint Committee on Cancer (AJCC)-7 T1-2N2b tonsillar cancer results in a low rate of contralateral nodal failure. Materials and Methods: This study was a retrospective chart review of patients with AJCC-7 T1-2N2b tonsillar cancer from 2 academic institutions who were treated with unilateral radiation. The primary endpoint was the contralateral nodal failure rate. Locoregional control, overall survival, and the need for gastrostomy tube placement were additional endpoints. Results: The study cohort included 66 patients treated between 2005 and 2016. The median follow-up time was 80.9 months; contralateral nodal failure occurred in 2/66 (3.0%) patients at 4.1 and 20.9 months, respectively. Both patients underwent salvage treatment with long-term subsequent survival. Overall locoregional control at both 2 and 5 years was 93.9% and the median duration of control was not reached. Overall survival at 5 years was 92.4%. Conclusions: The use of unilateral radiation for AJCC-7 T1-2N2b tonsillar cancer resulted in low rates of contralateral nodal failure. This outcome demonstrates the safety of considering unilateral radiation treatment in patients with a relatively high ipsilateral nodal burden.