Advanced Radiation Techniques in the Treatment of Esthesioneuroblastoma: A 7-Year Single-Institution's Clinical Experience

Abstract

(1) Background: Esthesioneuroblastoma (ENB) is a rare tumor entity originating from the olfactory neuroepithelium. There is a scarcity of data about different treatment strategies. Intensity modulated radiotherapy (IMRT) and carbon ion radiotherapy (CIRT) are advanced radiation techniques that might improve local tumor control. (2) Methods: This retrospective analysis contained 17 patients with ENB (Kadish stage ≥ C: 88%; n = 15). Four patients had already undergone previous radiotherapy (RT). The treatment consisted of either IMRT (n = 5), CIRT (n = 4) or a combination of both techniques (n = 8). Median follow-up was 29 months. (3) Results: In patients that had not been irradiated before (n = 13), calculated overall survival (OS) and progression free survival (PFS) rates after 48 months were 100% and 81% respectively (Kaplan-Meier estimates). Two of four patients that underwent reirradiation died after RT, presumably due to tumor progression. Besides common toxicities, five patients (30%) showed mostly asymptomatic radiation-induced brain changes, most likely due to a disturbance of the blood-brain barrier. (4) Conclusions: Our results demonstrate that IMRT, CIRT, a combined approach of IMRT and CIRT as well as reirradiation with CIRT seem to be feasible and effective treatment methods in ENB.

Keywords: carbon ion radiation; esthesioneuroblastoma; olfactory neuroblastoma; particle therapy; radiotherapy.

Figure 1

Representative comparison of carbon ion radiotherapy (CIRT) and intensity modulated radiotherapy (IMRT) plans to show general differences. Comparing radiation plans of CIRT and IMRT, carbon ion radiation shows a remarkable higher dose conformity than photon irradiation.

Figure 2

Overall survival (OS), progression free survival (PFS) and local recurrence free survival (LRFS) of patients with esthesioneuroblastoma (ENB). The presented patients (n = 13) had not been irradiated before (group A). (a) OS of patients with ENB after radiotherapy (RT) (group A). (b) PFS of patients with ENB (group A). Progression was defined as both local or distant tumor recurrence. (c) LRFS of patients with ENB (group A). Local recurrence was defined as tumor recurrence at the primary tumor site (local failure). Regional failure was not included. (d) PFS of patients with ENB after RT (group A). Comparison between photons and a bimodal radiation technique consisting of photons plus carbon ion boost radiation. PFS differences could not be calculated due to the limited number of events.

Figure 3

Radiation-induced cerebral contrast agent enhancement. Baseline and follow-up MRI scan of a patient with esthesioneuroblastoma (ENB). 23 months after radiotherapy a new cerebral contrast agent enhancement (white arrow) could be detected. In comparison with the initially treated radiation plan (MRI scan on the right) the lesion occurred in an irradiated region of the right frontal lobe at the edge of the 95%-isodose representing 57 Gy (RBE, 71.25 Gy EQD2). A radiation-induced disturbance of the blood-brain barrier or even radiation necrosis is probable.