Fractionated stereotactic radiotherapy in low-grade astrocytomas: long-term outcome and prognostic factors.

PURPOSE

To evaluate outcome after fractionated stereotactic radiotherapy (RT) of patients with World Health Organization Grade 2 astrocytoma in terms of progression-free survival, overall survival, toxicity, quality of life, and prognostic factors.

METHODS AND MATERIALS

Between 1984 and 2000, 143 patients with histologically proven Grade 2 astrocytoma were treated with fractionated stereotactic RT at our institution. The evaluation of the quality of life and toxicity was based on neurologic examinations and the Karnofsky performance score. Univariate analysis was performed on seven potential prognosticators and multivariate analysis on four prognosticators.

RESULTS

The median follow-up was 44 months. The actuarial overall survival and progression-free survival was 58% and 39% at 5 years, respectively. Out-of-field recurrences occurred in 1 patient (1.2%). We did not observe a dose-response relationship. Overall survival and progression-free survival were significantly correlated with the absence of contrast media enhancement before RT (p <0.01). Toxicity was mild and included severe side effects of European Organization for Research and Treatment of Cancer/Radiation Therapy Oncology Group Grade 3 in only 4 patients (2.8%). The Karnofsky performance score improved in most patients.

CONCLUSION

Fractionated stereotactic RT is effective and has low toxicity in the treatment of Grade 2 gliomas. The rate of field border recurrences was not increased compared with after conventional RT. Exceeding the tumor dose did not improve the tumor control rate but did enhance toxicity. Pretherapeutic contrast media enhancement should be interpreted as a sign of higher grade tumor elements.