Extent of Resection and Role of Adjuvant Radiotherapy in Olfactory Neuroblastoma Without Definite Radiologic Evidence of Dural Invasion

Objectives: To evaluate the impact of the extent of resection and adjuvant radiotherapy (RT) on treatment outcomes in patients with early-stage olfactory neuroblastoma (ONB) without definite dural invasion. Methods: A retrospective review of ONB cases from two centers within a single institution between 1992 and 2023 was performed. Clinicopathologic data included tumor stage, grade, treatment modalities, margin status, follow-up time, and survival. Survival outcomes, including overall survival (OS), disease-free survival (DFS), and local recurrence-free survival (LFS), were analyzed. Results: Of 118 ONB patients, 38 were included in the final cohort, with most (76.3%) classified as modified Kadish (mKadish) stage A or B. The 10-year DFS and LFS rates were 68.5% and 89.7%, respectively. No local recurrence occurred in patients who underwent transdural resection with negative margins, regardless of adjuvant RT. Extradural resection with adjuvant RT significantly improved LFS compared to extradural resection alone (log-rank p = 0.032). Pathologic dura involvement was identified in four (19.0%) of 21 patients who underwent transdural resection. No significant difference in oncologic outcomes between unilateral and bilateral resections was observed when transdural resection was performed for unilateral disease. Conclusions: Transdural resection with negative surgical margins, regardless of adjuvant RT, or extradural resection with adjuvant RT, demonstrated excellent local control. Extradural resection alone was associated with a higher risk of local recurrence. Unilateral transdural resection can be feasible for unilateral disease.