Risk factors for distant metastasis in squamous cell carcinoma of the oral cavity.

Purpose: This study aimed to identify risk factors for distant metastasis (DM) in patients with squamous cell carcinoma of the oral cavity.

Materials And Methods: A retrospective analysis of 516 patients with squamous cell carcinoma of the oral cavity from 1986 through 2009 was performed. DM was classified as 2 types based on whether patients had locoregional failure (LRF). The frequency and clinicopathologic risk factors for the 2 types of DM were evaluated separately using univariate χ(2) tests and multivariate logistic regression models. Overall survival was evaluated with the Kaplan-Meier method and compared by the log-rank test.

Results: Fifty-four patients (10%) developed DM, 16 with isolated DM and 38 with DM with LRF. The 5-year survival rate from a DM diagnosis in patients with isolated DM was 13%, significantly higher than the rate of those with DM with LRF (0%; log-rank test, P < .05). Multivariate analysis indicated unique risk factors and common risk factors for the 2 types of DM. The common factors were nonsurgical treatment and the presence of pathologic positive nodes. The unique factors for isolated DM were histologic grade G3 and the later treatment period (after 1998). Conversely, the unique factor for DM with LRF was extracapsular spread.

Conclusion: The risk of isolated DM development after 1998 was 2.6 times higher than that before 1997. Histologic grade G3 and the presence of pathologic positive nodes may play a causative role in isolated DM.