Image-guided, intensity-modulated radiation therapy (IG-IMRT) for skull base chordoma and chondrosarcoma: preliminary outcomes

Abstract

Background: We report our preliminary outcomes following high-dose image-guided intensity modulated radiotherapy (IG-IMRT) for skull base chordoma and chondrosarcoma.

Methods: Forty-two consecutive IG-IMRT patients, with either skull base chordoma (n = 24) or chondrosarcoma (n = 18) treated between August 2001 and December 2012 were reviewed. The median follow-up was 36 months (range, 3-90 mo) in the chordoma cohort, and 67 months (range, 15-125) in the chondrosarcoma cohort. Initial surgery included biopsy (7% of patients), subtotal resection (57% of patients), and gross total resection (36% of patients). The median IG-IMRT total doses in the chondrosarcoma and chordoma cohorts were 70 Gy and 76 Gy, respectively, delivered with 2 Gy/fraction.

Results: For the chordoma and chondrosarcoma cohorts, the 5-year overall survival and local control rates were 85.6% and 65.3%, and 87.8% and 88.1%, respectively. In total, 10 patients progressed locally: 8 were chordoma patients and 2 chondrosarcoma patients. Both chondrosarcoma failures were in higher-grade tumors (grades 2 and 3). None of the 8 patients with grade 1 chondrosarcoma failed, with a median follow-up of 77 months (range, 34-125). There were 8 radiation-induced late effects-the most significant was a radiation-induced secondary malignancy occurring 6.7 years following IG-IMRT. Gross total resection and age were predictors of local control in the chordoma and chondrosarcoma patients, respectively.

Conclusions: We report favorable survival, local control and adverse event rates following high dose IG-IMRT. Further follow-up is needed to confirm long-term efficacy.

Keywords: chondrosarcoma; chordoma; image-guided intensity modulated radiotherapy; photon radiation.

© The Author(s) 2014. Published by Oxford University Press on behalf of the Society for Neuro-Oncology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Figures

Fig. 1.

(A) Axial T1-weighted MRI of a skull base chordoma involving the clivus and cavernous sinus that was subtotally resected. The patient received 78 Gy in 39 fractions with IG-IMRT. (B) Axial treatment planning CT slice with the dose distribution and representative isodose lines and (C) sagittal treatment planning CT slice with the dose distribution and representative isodose lines.

Fig. 2.

Kaplan–Meier survival curve illustrating OS by tumor type.

Fig. 3.

Cumulative incidence curve of tumor recurrence according to tumor type.