Long-term survival outcomes and recurrence patterns of olfactory neuroblastoma: A 13-year experience at a single...

Olfactory neuroblastoma (ONB), also known as esthesioneuroblastoma, is a rare malignant neoplasm of the nasal vault and anterior skull base. The results of treatment for ONB are relatively good; however, regional and distant metastases can develop several years after definitive treatment. This study aimed to validate the treatment modality of ONB for oncological outcomes, especially for regional recurrence.

We retrospectively reviewed the medical records of 22 patients diagnosed with ONB at Kyoto University Hospital between 2009 and 2020. Descriptive statistics were calculated, and Kaplan-Meier curves were used.

The median follow-up time was 58.2 months. One (4.5%) patient was clinically node positive, (cN+) and the remaining 21 (95.5%) were clinically node negative (cN0) at presentation. Eighteen patients underwent an endoscopic endonasal approach (EEA) for primary resection, and the remaining four patients underwent a combined EEA and transcranial approach. Elective neck dissection was not performed for 21 patients with cN0 ONB, whereas unilateral neck dissection with removal of ipsilateral lateral retropharyngeal node was performed for one patient with cN+ ONB. Postoperative radiotherapy without concurrent chemotherapy was performed only at the primary tumor bed for 21 patients with cN0 ONB, and at the primary tumor bed and bilateral neck for one patient with cN+ ONB. The 5-year overall, disease-specific, and disease-free survival rates were 94.1%, 100%, and 69.6%, respectively. No patients developed local recurrence, but 6 (27.2%) patients experienced recurrence with a median time to recurrence of 36.4 months, including four and two patients who initially developed regional recurrences and bone metastases, respectively. Five (22.7%) patients had delayed neck recurrence. The salvage rate was only 60.0% in the five patients who had delayed neck recurrence. Regarding the level of delayed neck recurrence, 4 (18.2%) patients had lateral retropharyngeal lymph node metastases.

Patients with ONB have excellent survival outcomes after endoscopic surgical resection of the primary lesion with postoperative radiotherapy only to the primary tumor bed. Despite excellent survival, delayed neck recurrence, including the lateral retropharyngeal lymph node, remains high. Because salvage surgery for lateral retropharyngeal lymph node recurrence is sometimes technically difficult, it may be better to extend the field of postoperative radiotherapy from the primary tumor bed only to include bilateral lateral retropharyngeal lymph node regions in patients with clinically N0 ONB. Further prospective studies with a large number of patients are needed to determine the extent of postoperative radiotherapy.