Survival and Recurrence for Patients Undergoing Surgery of Skull Base Intracranial Metastases

Objective: Skull base metastases (SBMs) are relatively rare lesions. This rarity has precluded understanding the prognosis for patients who develop these lesions. Many of these patients with SBM are not offered surgery because of their presumed poor prognoses. The goals of this study were (1) to understand clinical differences between patients who underwent surgery for SBM versus intraparenchymal metastases, and (2) to evaluate differences in outcomes between these patient populations.

Methods: Adult patients who underwent surgery for an intracranial metastasis at an academic tertiary care institution between 1997 and 2011 were retrospectively reviewed. SBMs were defined as those metastases involving bone of the anterior cranial fossa, orbit, sella, sphenoid wing and sinuses, clivus, and petrous bone. Differences between patients with and without SBM were compared using Fisher exact test for categorical variables and Student t-test for continuous variables. Survival as a function of time was plotted using the Kaplan-Meier method, and survival rates were compared using log-rank analysis. Variables with P < 0.05 were considered statistically significant.

Results: A total of 708 patients underwent surgery for an intracranial metastasis. Of these 708 patients, 29 (4%) had SBM. Three (10%) of these 29 involved the anterior skull base; 7 (24%) the sella; 6 (21%) the orbit; 2 (7%) the sphenoid wing; 3 (10%) the clivus; 4 (14%) the petrous bone; and 4 (14%) the maxillary, ethmoid, or sphenoid sinuses. Patients with SBM were less likely to present with seizures (P = 0.01) and motor deficit (P = 0.0005) than patients without SBM. Additionally, patients with SBM were more likely to have primary bone tumors (P = 0.004), thyroid cancer (P = 0.05), and unknown primary cancers (P = 0.05). Following surgery, these patients were less likely to undergo gross total resection (P = 0.0000). In regards to outcomes, there was no difference in median survival (10.0 vs. 9.2 months; P = 0.48) and local progression-free survival (PFS) (12-month local PFS, 75% vs. 76.8%; P = 0.42) between patients with and without SBM. However, patients with SBM had improved distal PFS compared with patients without SBM (12-month distal PFS 82.9% vs. 53.4%; P = 0.04).

Conclusions: Patients with SBM are relatively rare. Despite their rarity, these patients can tolerate surgery with minimal morbidity and mortality. Moreover, they have similar prognoses to patients without SBM.