Patterns of failures after surgical resection in olfactory neuroblastoma

Introduction: Patterns of failure in patients with olfactory neuroblastoma (ONB) according to two surgical approaches, craniofacial resection (CFR) and endoscopic surgery (ENDO), have yet to be analyzed. Methods: We retrospectively reviewed 28 patients with surgically treated ONB between January 1995 and October 2017. Fourteen (50.0%) patients underwent CFR (9 CFR alone, 5 ENDO-assisted CFR) and 14 (50.0%) underwent ENDO. Nineteen (67.9%) patients underwent post-operative radiotherapy (RT). Results: At a median follow-up of 53.8 months (range 10.4–195.3), the 5-year progression-free survival (PFS) and 10-year overall survival were 37.3% and 57.5%, respectively. Patients with adjuvant RT had a 5-year PFS of 46.7%, whereas those treated with surgery alone had a 5-year PFS of 19.4% (p = 0.01). Locoregional failure (LRF) occurred in ten patients (median 59.6 months after initial diagnosis; range 12.7–59.7). Neck node metastasis occurred in 25.0% (7 of 28). Five patients with ENDO showed LRF and underwent proper subsequent treatments with either surgery or adjuvant RT. Approximately 35.7% patients (five patients) in the CFR group experienced distant metastasis in the intracranial dura region (median 116.4 months after initial diagnosis; range 2.6–142.4). Three of four patients who developed LRF after CFR developed dura-based metastasis. Conclusions: Both dura-based and neck node metastasis in the delayed phase were distinct patterns of failure in ONB. Patterns of recurrence differed based on surgical approach; dura-based metastases were common after CFR. LRF was the distinct failure pattern in ENDO, but could be successfully salvaged. Treatment outcome was improved considerably with RT following surgical resection.