Object: The role of surgery and adjuvant radiation therapy for cranial base chordomas is not well established. This meta-analysis measures the relationship of complete resection and type of adjuvant radiation therapy to 5-year progression-free survival (PFS) and overall survival (OS) of cranial base chordomas.
Methods: A systematic MEDLINE search (1999-present) yielded 23 observational studies and 807 patients who fit inclusion criteria. The following analyses were performed: 1) Kaplan-Meier 5-year PFS and OS compared based on the extent of resection and type of adjuvant radiation therapy using the log-rank method; 2) a random-effects model comparing 5-year PFS with complete or incomplete resection; and 3) paired z-test comparisons of weighted average 5-year OS and PFS grouped by type of adjuvant radiation therapy.
Results: The weighted average follow-up was 53.6 months. The weighted average 5-year PFS and OS were 50.8% and 78.4%, respectively. Complete resection conferred a higher 5-year PFS than incomplete resection from the random effects model (mean difference in PFS 20.7%; 95% CI 6.57%-34.91%). Patients with incomplete resection were 3.83 times more likely to experience a recurrence (95% CI 1.63-9.00) and 5.85 times more likely to die (95% CI 1.40-24.5) at 5 years versus patients with complete resection. There was no difference in 5-year OS by type of adjuvant radiation, although 5-year PFS was lower in patients receiving Gamma Knife surgery relative to carbon ion radiotherapy (p = 0.042) on paired z-test. No survival difference occurred between radiation therapy techniques on Kaplan-Meier analysis of compiled patient data.
Conclusions: Patients with complete resection of cranial base chordomas have a prolonged 5-year PFS and OS. Adjuvant proton-beam, carbon ion, and modern fractionated photon radiation therapy techniques offered a similar rate of PFS and OS at 5 years.