Regional Recurrence Rates in Clinically Node Negative Sinonasal Cancers Without Elective Neck Treatment

Summary: Sinonasal malignancies represent a rare and histologically diverse subset of head and neck cancers. Optimal management entails maximal safe resection followed by adjuvant radiation +/- chemotherapy, however there is controversy regarding radiation treatment volumes in the adjuvant setting. In this retrospective review, we sought to examine the rates of regional recurrence in clinically node negative (cN0) sinonasal cancer patients treated with adjuvant radiation to the postoperative bed, but did not receive elective neck dissection (eND) and/or elective nodal irradiation (eNI). We analyzed 40 consecutive patients with clinical or pathologic T1-4N0M0 sinonasal cancer, treated with curative intent from 2007-2021. Seven out of the forty patients had neck dissections with or without elective nodal coverage in their adjuvant radiation treatment and were excluded from the study. Of the 33 patients included in the study, only 10 patients (30%) received either neoadjuvant or concurrent chemotherapy with their radiation treatments. Median RT dose was 60 Gy [56.4 – 69.6 Gy], and median number of fractions was 50 [28-58]. Primary endpoint was regional progression free survival (RPFS). Secondary endpoints included, local progression free survival (LPFS), distant metastasis free survival (DMFS) and overall survival (OS). The median age was 61 years and median time of follow up was 6 years. Squamous cell carcinoma (SCC) and Esthesioneuroblastoma (ENB) were the most common histologic subtypes. Only Five patients [15 %] had observed recurrences in the untreated neck and were mostly T4 disease. All five patients were successfully salvaged. The histologic subtypes with observed regional recurrences were ENB (3 patients), SMARCB1 deficient/small cell neuroendocrine carcinoma (2 patients). Level 1b, II and retropharyngeal nodes were the sites of observed regional recurrences. Median time to regional recurrence was 4 years. RPFS at 2 and 5 years were 88% and 76% respectively. LPFS at 2 and 5 years were 82% and 58% respectively. DMFS at 2 and 5 years were 88% and 70% respectively. OS at 2 and 5 years were 94% and 79% respectively. We found low to moderate regional recurrence rates in cN0 patients who did not receive eND or eNI. Of note, there were no regional recurrences in patients with SCC regardless of T stage. More research is needed to identify clinical and histologic features of sinonasal cancers that may be candidate for omission or treatment of the elective neck in these patients. osagie s. Igiebor (he/him/his), n/a (Presenting Author) - Medical university of south carolina; Justin steinman, MD (Co-Author) - Alabama cancer care; joseph adedigba, MD (Co-Author) - Medical university of south carolina; John Kaczmar, MD (Co-Author) - Medical university of south carolina; Alexandra Kejner, MD (Co-Author) - Medical university of south carolina; William Abergotti, MD (Co-Author) - Medical university of south carolina; Jason Newman, MD (Co-Author) - Medical university of south carolina; Jennifer Harper, MD (Co-Author) - Medical university of south carolina; Bhishamjit Chera, MD (Co-Author) - Medical university of south carolina