Management of Soft Tissue Sarcomas of the Skull Base: Factors Impacting Tumor Control and Disease-Specific Survival

Background: Soft tissue sarcomas (STS) of the skull base are rare and, as such, there is limited published knowledge and data to guide the surgical management of patients with these tumors.

Objective: This study was aimed to determine the factors that affect tumor control rates and survival in patients undergoing surgical resection of soft tissue sarcomas of the skull base.

Methods: Retrospective review of prospectively collected data for 60 patients with soft tissue sarcomas of the skull base, surgically treated at our institution between 1969 and 2016. Tumor and treatment-related factors were collected and assessed for impact on progression-free survival (PFS) and disease-specific survival (DSS). Tumors were graded according to the Federation Nationale des Centes de Lutte Contre Le Cancer (FNCLCC) system, which is used to categorize STS subtypes according to histologic features predictive of biologic behavior. Kaplan–Meier estimates of PFS and DSS were calculated and survival curves were compared using the log rank test. The Cox proportional hazards model was used in the univariate and multivariate analyses to identify predictive factors.

Results: Sixty patients with a mean age of 35 (range, 2–75) years and a median presenting Karnofsky’s performance score (KPS) of 90 were identified for study inclusion. Six (10%) patients were FNCLCC grade 1, 18 (30%) were FNCLCC grade 2, and 36 (60%) were FNCLCC grade 3. The most common histologic diagnoses represented were hemangiopericytoma (23.3%), rhabdomyosarcoma (20%), malignant fibrous histiocytoma (10%) and liposarcoma (10%). Mean length of follow-up was 73.7 months ± 57.6 (SD). Five-year PFS and DSS rates were 45 and 60%, respectively. Ten-year PFS and DSS rates were 29 and 32%, respectively. Recurrence occurred in 19 (31.7%) patients. The most common cause of treatment failure was local recurrence, in 12 of 60 patients (20%). In the multivariate analysis for the entire cohort, metastasis on presentation was an independent predictor of poor DSS (hazard ratio [HR] = 3.76, 95% confidence interval [CI]: 1.53–9.21). For patients who presented without metastasis (n = 52), prior radiation treatment (HR = 0.009, CI: 0.023–0.590), cavernous sinus involvement (HR = 0.051, CI: 0.010–0.270) were negative predictors while gross total resection (GTR) with negative margins (HR = 9.416, CI: 1.276–69.514) was a positive predictor of PFS. For DSS, brain invasion (HR = 0.254, CI: 0.089–0.729) was the only independent predictor of survival.

Conclusion: The most common cause of treatment failure for patients with soft tissue sarcomas of the skull base is local recurrence, which defines the goals of treatment. Metastasis at presentation was an independent predictor of poor DSS. For patients presenting with local disease only, prior radiation treatment, cavernous sinus involvement, and GTR with negative margins were independent predictors of PFS whereas brain invasion was an independent predictor of poor DSS. This data can be used to inform surgical decision making and counseling for patients with soft tissue sarcomas of the skull base.