Feasibility of omitting contralateral neck irradiation in patients with node‐negative sinonasal squamous cell carcinoma crossing the midline

Background Identifying the lymph node target volume in patients with node‐negative sinonasal squamous cell carcinoma (SNSCC) crossing the midline poses a challenge. This study aims to address this. Methods We retrospectively reviewed clinically N0 patients with tumors crossing the midline who received elective neck irradiation (ENI) from two centers between 1999 and 2019. The main endpoint was regional relapse‐free survival (RRFS). Results We included 104 patients: 64 received bilateral ENI, and 40 received ipsilateral‐only ENI (median follow‐up time was 89.99 and 95.01 months, respectively). At 5 years, the RRFS rates were comparable (57.68% vs. 55.83%, p = 0.372), as were the contralateral RRFS (57.68% vs. 61.62%, p = 0.541). Five‐year OS, LRFS, and DMFS showed no significant difference between two groups. Conclusions Our findings provide preliminary evidence suggesting the potential for avoiding contralateral ENI in SNSCC patients with midline crossing tumors who undergo ipsilateral ENI, covering at least level II. Validation through future prospective studies is necessary.