One-sided argument.

Top Line: What is the risk of contralateral neck failure following unilateral neck treatment for tonsillar cancer?

The Study: Two large retrospective studies from Princess Margaret inform our use of unilateral neck radiation for T1-2N0 and T1-2N0-2b tonsillar cancer. The latter of these studies specifically included node positive patients stratified according to HPV status and found that contralateral neck failures were rare (2%). Here’s another retrospective series from MDACC, which includes 403 patients treated either definitively or adjuvantly for tonsillar cancer between 2000 and 2018. HPV status was available in 75% of patients of whom 98% were HPV positive. Most patients (85%) were node positive including 14% with N2a and 45% with N2b disease. Over half (52%) were treated in the post-op setting and nearly a third of patients overall (32.5%) received concurrent chemotherapy. The target volume included the primary tumor site and ipsilateral levels II-IV and VII when node negative and levels IB-IV and VII when node positive. With a median follow-up of 5.8 years, only 3% of patients experienced a failure in the neck (1% ipsilateral, 2% contralateral). The 5-year rate of local control was 97% and regional control was 96%. Among patients with N2b disease (multiple ipsilateral nodes), the rate of contralateral neck recurrence was just 3%.

TBL: This large retrospective study supports the safety and efficacy of unilateral neck radiation for lateralized tonsillar cancers with a <5% risk of contralateral neck recurrence even among those with multiple positive nodes. | Taku, Int J Radiat Oncol Biol Phys 2022