Prognostic factors in oral cavity cancer with skull base recurrence

Recurred oral cavity cancer at the skull base is complicated to treat due to difficult surgical approach and possible dural invasion. Therefore, initial curative treatment is of most importance and it would be helpful to know cases that would likely recur before treatment. We tried to identify prognostic factors that can predict skull base recurrence after initial treatment, to find out cases that need more aggressive initial treatment.

This retrospective study was performed on 51 patients diagnosed as squamous cell carcinoma in the oral cavity, and they underwent surgery and adjuvant radiotherapy. Variables associated with clinical findings, imaging studies, and pathologic results were analyzed to identify factors related to skull base recurrence.

Recurrences occurred in 21% (11) cases, and skull base invasion in 5 of these recurred cases. Tumor location, clinical T stage, retromolar trigone (RMT) invasion, bone invasion, perineural invasion, positive resection margin, endolymphatic tumor emboli, and medial and lateral pterygoid muscle invasion were found to be significant prognostic factors by univariate analyses. Among those factors, medial pterygoid muscle invasion and positive resection margin remained independent predictors of skull base recurrence with multivariate analyses by Cox regression.

Patients with medial pterygoid muscle invasion or a positive resection margin have a high risk of skull base invasion during tumor recurrence. Therefore, careful evaluation and aggressive management are needed to prevent skull base invasion in cases that recur.