KEY POINTS
- This two-centre retrospective series included 58 patients with well-lateralised oropharyngeal SCC treated definitively with unilateral neck RT between 2015 and 2021. 94.8% were p16 positive, and 96.5% had tonsillar primaries.
- Nodal disease was substantial: 43/58 patients (74.1%) had TNM7 N2b disease. Among evaluable N2b patients, 50% had a node ≥3 cm, 43% had ≥3 involved nodes and 40% had disease outside levels II/III.
- Most patients received 65 Gy in 30 fractions, and 79% received concurrent systemic therapy. Median follow-up was 72 months.
- Contralateral neck-only recurrence occurred in only 2/58 patients (3.4%). Both events occurred in N1 disease, and neither patient completed the planned systemic therapy.
- Most importantly, 0/43 N2b patients developed contralateral neck-only recurrence, including patients meeting one or more predefined high nodal-burden criteria.
- Both patients with isolated contralateral recurrence underwent salvage neck dissection and remained disease-free for more than five years after salvage.
- Overall, 13 patients recurred: 9 locoregionally and 4 distantly. Among N2b patients, the dominant failures remained primary-site or ipsilateral-neck rather than contralateral-neck relapse.
- The subgroup meeting all three high-burden criteria had a numerically higher locoregional recurrence rate of 33% (2/6), but event numbers were far too small to define a new risk group.
CLINICAL TAKEAWAY
For a truly well-lateralised, predominantly HPV-associated tonsillar cancer with a clinically negative opposite neck, ipsilateral nodal burden alone may not mandate bilateral irradiation. The cohort is small and retrospective and contains almost no HPV-negative or non-tonsillar disease, so rigorous laterality assessment remains essential before applying this approach more broadly.