Prognosis of Distant Metastatic Sites in Anterior Skull Base Malignancies

 This study aimed to provide information regarding the prognosis of patients presenting with metastatic anterior skull base malignancies based upon histology and site of distant metastasis (DM).  The National Cancer Database was queried for patients with anterior skull base malignant neoplasms with DM.  Prognosis was compared between site of DM and tumor histologies. A multivariable Cox proportional hazards model was used to identify prognostic factors for overall survival (OS).  A total of 481 patients were identified. Lung was the most common site of DM (24.9%), followed by bone (22.2%), liver (5.6%), and brain (2.5%). Lung was the most common site for squamous cell carcinoma (SCCa) (28.3%), melanoma (37.7%), and adenoid cystic carcinoma (ACC; 31.4%). The median survival for patients presenting with metastatic disease regardless of tumor histology was 9.0 months (95% confidence interval [CI]: 8.2-10.3), and patients with metastasis to the liver had the best median survival at 15.5 months (95% CI: 10.5-25.6). The median survivals for the most common histologies, SCCa, melanoma, and ACC were 8.2 months (95% CI: 5.5-10.2), 10.5 months (95% CI: 8.7-14.1), and 15.0 months (95% CI: 11.1-61.1), respectively. Multivariable analysis demonstrated worse overall survival (OS) for older patients, higher Charlson-Deyo comorbidity scores, and tumors with higher grade and T stage. Compared with metastasis to bone, lung metastasis had better OS on multivariable analysis (hazard ratio [HR]: 0.70, 95% CI: 0.51-97). Adenoid cystic carcinoma had improved OS compared with SCCa (HR: 0.62, 95% CI: 0.39-99).  Tumor histology, metastatic sites, and several disease factors affected prognosis in anterior skull base malignancies with DM.