Prognosis of Distant Metastatic Sites in Anterior Skull Base Malignancies

Objectives: Workup and treatment of malignant anterior skull base neoplasms requires evaluation for distant metastasis (DM). This study aimed to investigate the prognosis for patients presenting with metastatic anterior skull base malignancies based on histology and site of DM.

Methods: The National Cancer Database (NCDB) was queried for patients with anterior skull base malignant neoplasms with DM diagnosed between 2004 and 2015. The prognosis of these patients was compared between the sites of metastasis (i.e., bone, brain, liver, lung, other) and primary tumor histologies. A multivariable Cox proportional hazards model was used to identify the prognostic factors for overall survival (OS).

Results: A total of 481 patients with metastatic anterior skull base malignancies were identified. Lung was the most common site of DM overall (24.9%), followed by bone (22.2%), liver (5.6%), and brain (2.5%); 44.7% of patients had other or unknown sites of DM. When specified, the most common tumor histology types included squamous cell carcinoma (SCCa) (34.5%), melanoma (16.0%), and adenoid cystic carcinoma (7.3%). When site of metastasis was indicated, lung was the most common site for SCCa (28.3%), melanoma (37.7%), and adenoid cystic carcinoma (31.4%); the most common site of metastasis for carcinoma not otherwise specified (NOS) and undifferentiated carcinoma (SNUC) was bone at 34.1 and 33.3%, respectively. The median survival for all patients presenting with metastatic disease regardless of tumor histology was 9.0 months (CI: 8.2–10.3), and patients with metastasis to the liver had the best median survival at 15.5 months (CI: 10.5–25.6). The median survivals for metastatic SCCa, melanoma, and adenoid cystic carcinoma were 8.2 months (CI: 5.5–10.2), 10.5 months (CI: 8.7–14.1), and 15.0 months (CI: 11.1–61.1), respectively. Multivariable analysis demonstrated worse 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 (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).

Conclusion: Tumor histology, metastatic sites, and several disease factors affected prognosis in anterior skull base malignancies with DM. Due to differences in the most common sites of metastasis, the underlying tumor pathology should be considered when selecting the optimal radiographic evaluation for DM.

Fig. 1 Unadjusted Kaplan–Meier chart for overall survival of patients with metastatic anterior skull base malignancies based on sites of distant metastasis.

Fig. 2 Unadjusted Kaplan–Meier chart demonstrating overall survival of patients with metastatic anterior skull base malignancies for the most common tumor histologies.

Publication History

Article published online:
12 February 2021