Is gross-total resection sufficient treatment for posterior fossa ependymomas?

The goals of this study were to analyze outcomes in patients with posterior fossa ependymomas, determine whether gross-total resection (GTR) alone is appropriate treatment, and evaluate the role of radiation therapy.

All patients with newly diagnosed intracranial ependymomas treated at Barrow Neurological Institute between 1983 and 2002 were identified. Those with supratentorial primary lesions, subependymomas, or neuraxis dissemination were excluded. Forty-five patients met the criteria for the study. Gross-total resection was accomplished in 32 patients (71%) and subtotal resection (STR) in 13 (29%). Radiation therapy was given to 25 patients: 13 following GTR and 12 after STR. The radiation fields were craniospinal followed by a posterior fossa boost in six patients and posterior fossa or local only in the remaining patients. With a median follow-up period of 66 months, the median duration of local control was 73.5 months with GTR alone, but has not yet been reached for patients with both GTR and radiotherapy (p = 0.020). The median duration of local control following STR and radiotherapy was 79.6 months. The 10-year actuarial local control rate was 100% for patients who underwent GTR and radiotherapy, 50% for those who underwent GTR alone, and 36% for those who underwent both STR and radiotherapy, representing significant differences between the GTR-plus-radiotherapy and GTR-alone cohorts (p = 0.018), and between the GTR-plus-radiotherapy and the STR-plus-radiotherapy group (p = 0.003). There was no significant difference in the 10-year actuarial local control rate between the GTR-alone and STR-plus-radiotherapy cohorts (p = 0.370). The 10-year overall survival was numerically superior in patients who underwent both GTR and radiotherapy: 83% compared with 67% in those who underwent GTR alone and 43% in those who underwent both STR and radiotherapy. These differences did not achieve statistical significance. Univariate analyses revealed that radiotherapy, tumor grade, and extent of resection were significant predictors of local control.

Gross-total resection should be the intent of surgery when it can be accomplished with an acceptable degree of morbidity. Even after GTR has been confirmed with postoperative imaging, however, adjuvant radiotherapy significantly improves local control. The authors currently recommend the use of postoperative radiotherapy, regardless of whether the resection is gross total or subtotal.