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 nor mal tissue-sparing capability of 3-dimensional (3-D) treatment plannin g 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 mal ignant tumors of the paranasal sinuses as all or part of initial treat ment. Fifteen unresectable patients were treated with primary radiothe rapy to a median prescribed total dose of 68.4 Gy. Twenty-four patient s were treated with postoperative adjuvant radiotherapy for close marg ins (< 5 mm), microscopic or gross residual disease. The median prescr ibed total doses were 55.8 Gy, 59.4 Gy and 67.8 Gy, respectively. Glob e-sparing fields were used in the primary treatment plans of 37 patien ts (95%). The median follow-up is 4.5 years (range, 19-86 months). Res ults: For the unresectable patients who were treated with radiotherapy alone, the local control rate at 3 years is 32%. The actuarial overal l survivals at 3 and 4 years are 32%. For the patients who received po stoperative adjuvant radiotherapy, none of the five patients irradiate d for close surgical margins recurred locally. Three of the 14 with mi croscopic residual (21%) recurred locally at 26, 63, and 74 months fro m the start of irradiation. Four of the five with gross residual (80%) recurred locally with a median time to recurrence of 2 years. The loc al control rates at 3 and 5 years for the adjuvant group are 75% and 6 5%, respectively. The actuarial overall survival at 3 and 5 years are 65% and 60%, respectively. None of the first sites of local disease pr ogression were judged to have occurred outside the high-dose region. T here 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 re lated to irradiation. Conclusion: This study indicates that computed t omography-based 3-D radiotherapy can preserve critical structures unaf fected by tumor invasion and achieve the generally expected local cont rol rates when it is used as all or part of initial treatment for exte nsive malignant tumors of the paranasal sinus. The presence of gross d isease 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.