RADIOSURGERY FOR SKULL BASE MALIGNANCIES AND NASOPHARYNGEAL CARCINOMA

Purpose: Patients with skull base lesions present a challenging manage ment problem because of intractable symptoms and limited therapeutic o ptions, In 1989 we began treating selected patients with skull base le sions using linac stereotactic radiosurgery. In this study the efficac y and toxicity of this therapeutic modality is investigated. Methods a nd Materials: Forty-seven patients with 59 malignant skull base lesion s were treated with linac radiosurgery between 1989 and 1995, Eleven p atients were treated for primary nasopharyngeal carcinoma using radios urgery as a boost (7 Gy-16 Gy, median: 12 Gy) to the nasopharynx after a course of fractionated radiotherapy (64.8-70 Gy) without chemothera py. Another 37 patients were treated for 48 skull base metastases or l ocal recurrences from primary head and neck cancers, Eight of these pa tients had 12 locally recurrent nasopharyngeal carcinoma lesions occur ing 6-96 months after standard radiotherapy, including one patient wit h nasopharyngeal carcinoma who developed a regional relapse after radi otherapy with a stereotactic boost, Lesion volumes by CT or MRI ranged from 0 to 51 cc (median: 8 cc), Radiation doses of 7.0 Gy-35.0 Gy (me dian: 20.0 Gy) were delivered to recurrent lesions, usually as a singl e fraction. Results: All 11 patients who received radiosurgery as a na sopharyngeal boost after standard fractionated radiotherapy remain loc ally controlled (follow-up: 2-34 months, median: 18),However, one pati ent required a second radiosurgical treatment for regional relapse out side the initial radiosurgery volume, Thirty-three of 48 (69%) recurre nt/metastatic lesions have been locally controlled, including 7 of 12 locally recurrent nasopharyngeal lesions. Follow-up for all patients w ith recurrent lesions ranged from 1 to 60 months (median: 9 months), L ocal control did not correlate with lesion size (p = 0.80), histology (p = 0.78), or radiosurgical dose (p = 0.44). Major complications deve loped after 5 of 59 treatments (8.4%), including three cranial nerve p alsies, one CSF leak, and one trismus, Complications were not correlat ed with radiosurgical volume (p = 0.20), prior skull base irradiation (p = 0.90), or radiosurgery dose > 20 Gy (p = 0.49), Conclusion: Stere otactic radiosurgery is a reasonable treatment modality for patients w ith skull base malignancies, including patients with primary and recur rent nasopharyngeal carcinoma, The dose distribution obtained with ste reotactic radiosurgery provides better homogeneity than an intracavita ry implant when used as a boost for nasopharyngeal lesions, especially lesions which involve areas distant to the nasopharyngeal mucosa. (C) 1997 Elsevier Science Inc.