Intensity-Modulated Radiotherapy for Sinonasal Tumors: Ghent University Hospital Update

Purpose

To report the long-term outcome of intensity-modulated radiotherapy (IMRT) for sinonasal tumors.

Methods and Materials

Between July 1998 and November 2006, 84 patients with sinonasal tumors were treated with IMRT to a median dose of 70 Gy in 35 fractions. Of the 84 patients, 73 had a primary tumor and 11 had local recurrence. The tumor histologic type was adenocarcinoma in 54, squamous cell carcinoma in 17, esthesioneuroblastoma in 9, and adenoid cystic carcinoma in 4. The tumors were located in the ethmoid sinus in 47, maxillary sinus in 19, nasal cavity in 16, and multiple sites in 2. Postoperative IMRT was performed in 75 patients and 9 patients received primary IMRT.

Results

The median follow-up of living patients was 40 months (range, 8–106). The 5-year local control, overall survival, disease-specific survival, disease-free survival, and freedom from distant metastasis rate was 70.7%, 58.5%, 67%, 59.3%, and 82.2%, respectively. No difference was found in local control and survival between patients with primary or recurrent tumors. On multivariate analysis, invasion of the cribriform plate was significantly associated with lower local control (p = 0.0001) and overall survival (p = 0.0001). Local and distant recurrence was detected in 19 and 10 patients, respectively. Radiation-induced blindness was not observed. One patient developed Grade 3 radiation-induced retinopathy and neovascular glaucoma. Nonocular late radiation-induced toxicity comprised complete lacrimal duct stenosis in 1 patient and brain necrosis in 3 patients. Osteoradionecrosis of the maxilla and brain necrosis were detected in 1 of the 5 reirradiated patients.

Conclusion

IMRT for sinonasal tumors provides low rates of radiation-induced toxicity without blindness with high local control and survival. IMRT could be considered as the treatment of choice.

Introduction

Sinonasal tumors (tumors arising from the nasal cavity and paranasal sinuses) are a rare, histologically heterogeneous disease accounting for 5% of head-and-neck tumors and <1% of all malignancies 1, 2, 3. Remaining asymptomatic for a long period, most patients often present with locally advanced tumors extending into the neighboring organs and tissues. Local tumor extension in the vicinity of critical organs such as the eyes, optic nerves and chiasm, lacrimal glands, frontal and temporal lobes of the brain, brainstem, and pituitary gland makes treatment of sinonasal tumors extremely challenging. Patients usually undergo surgery followed by radiotherapy (RT). Primary or postoperative conventional RT for sinonasal tumors resulted in a local control and overall survival rate of about 59% and 40% at 5 years, respectively (4), and ≤33% of patients developed radiation-induced blindness 5, 6. The ability of intensity-modulated RT (IMRT) to generate concave dose distributions around the critical structures with a high-dose gradient outside the target underlies our hypothesis that IMRT for sinonasal tumors could minimize dry-eye syndrome and preserve vision without compromising local control. This hypothesis has been tested since 1998, when the first IMRT treatment was performed in the Department of Radiotherapy, Ghent University Hospital. The proposed IMRT strategy allowed for bilateral sparing of the lacrimal glands and optic structures (i.e., retina, optic nerves, and chiasm) (7) and resulted in avoidance of severe dry-eye syndrome (8) and minimization of visual impairment. Consistent with the greater prescription doses for IMRT-treated patients than for historical controls, greater rates of mid-term local control and survival were achieved compared with those after conventional RT for equal tumor stages (9). This study updates our long-term experience and reports on radiation-induced toxicity, local control, and survival in patients treated with IMRT between July 1998 and November 2006.