RESULTS OF PRIMARY AND ADJUVANT CT-BASED 3-DIMENSIONAL RADIOTHERAPY FOR MALIGNANT-TUMORS OF THE PARANASAL SINUSES

Purpose: This study reports our clinical experience supporting the normal tissue-sparing capability of 3-dimensional (3-D) treatment planning when applied to advanced neoplasms of the paranasal sinuses. Methods and Materials: Between 1986 and 1992, computed tomography (CT)-based 3-D radiotherapy was used to treat 39 patients with advanced stage malignant tumors of the paranasal sinuses as all or part of initial treatment. Fifteen unresectable patients were treated with primary radiotherapy to a median prescribed total dose of 68.4 Gy. Twenty-four patients were treated with postoperative adjuvant radiotherapy for close margins (< 5 mm), microscopic or gross residual disease. The median prescribed total doses were 55.8 Gy, 59.4 Gy and 67.8 Gy, respectively. Globe-sparing fields were used in the primary treatment plans of 37 patients (95%). The median follow-up is 4.5 years (range, 19-86 months). Results: For the unresectable patients who were treated with radiotherapy alone, the local control rate at 3 years is 32%. The actuarial overall survivals at 3 and 4 years are 32%. For the patients who received postoperative adjuvant radiotherapy, none of the five patients irradiated for close surgical margins recurred locally. Three of the 14 with microscopic residual (21%) recurred locally at 26, 63, and 74 months from the start of irradiation. Four of the five with gross residual (80%) recurred locally with a median time to recurrence of 2 years. The local control rates at 3 and 5 years for the adjuvant group are 75% and 65%, respectively. The actuarial overall survival at 3 and 5 years are 65% and 60%, respectively. None of the first sites of local disease progression were judged to have occurred outside the high-dose region. There was one case of mild osteoradionecrosis successfully treated with conservative treatment, one case of limited optic neuropathy and one case of possible radiation-induced cataract. There was no blindness related to irradiation. Conclusion: This study indicates that computed tomography-based 3-D radiotherapy can preserve critical structures unaffected by tumor invasion and achieve the generally expected local control rates when it is used as all or part of initial treatment for extensive malignant tumors of the paranasal sinus. The presence of gross disease was a major adverse prognostic factor in this study. Additional therapeutic maneuvers are essential to improve the local control and survival rate in patients with advanced paranasal sinus carcinomas.