EXPERIENCE IN CHARGED-PARTICLE IRRADIATION OF TUMORS OF THE SKULL BASE - 1977-1992

Purpose: To review the experience at University of California Lawrence Berkeley Laboratory in using charged particles to irradiate primary n eoplasms of the skull base and those extending to the skull base from the nasopharynx and paranasal sinuses. Methods and Materials: During t he period from 1977 to 1992, 223 patients were irradiated with charged particles at the Lawrence Berkeley Laboratory for tumors either arisi ng in or extending to the skull base, of whom 48 (22%) had recurrent l esions, either post previous surgery or radiotherapy. One hundred twen ty-six patients had lesions arising in the cranial base, mostly chordo ma (53), chondrosarcoma (27), paraclival meningioma (27) with 19 patie nts having other histologies such as osteosarcoma or neurofibrosarcoma . There were also 31 patients with primary or recurrent squamous carci noma of the nasopharynx extending to the skull base, 44 patients with major or minor salivary gland tumors, mostly adenocarcinoma, and 22 pa tients with squamous carcinoma of the paranasal sinuses, all with cran ial base extension. Results: Local control and survival appeared impro ved in tumors arising in the skull base, following the ability with ch arged particles to deliver high doses (mean of 65 Gy-equivalent) with relative sparing of the adjacent normal tissues. The Kaplan-Meier 5-ye ar local control was 85% for meningioma, 78% for chondrosarcoma, 63% f or chordoma and 58% for other sarcoma. Follow-up ranged from 4-191 mon ths with a median of 51 months. Conclusion: Charged particle radiother apy is highly effective ire controlling cranial base lesions which hav e have been partially resected. Better tumor localization with CT and MRI, improved 3-D treatment planning and beam delivery techniques have continued to reduce the level of serious complications and increase l ocal control and survival.