Distant metastases after definitive radiotherapy for squamous cell carcinoma of the head and neck

PURPOSE: To analyze parameters that influence the risk of distant metastases after definitive radiotherapy. METHODS: Between 1983 and 1997, 873 patients were treated with definitive radiotherapy and had follow-up for 2 years or more. Univariate and multivariate analyses were performed to evaluate risk factors that might influence the risk of distant metastases. RESULTS: The 5-year distant metastasis-free survival rate was 86%. Univariate analyses revealed that the risk of distant metastases was significantly influenced by gender (p =.0092), primary site (p =.0023), T stage (p <.0001), N stage (p <.0001), overall stage (p <.0001), level of nodal metastases in the neck (p <.0001), histologic differentiation (p =.0096), control above the clavicles (p <.0001), and time to locoregional recurrence (p <.0001). Multivariate analysis of freedom from distant metastases revealed that gender (p =.0390), T stage (p <.0001), N stage (p =.0060), nodal level (p <.0001), and locoregional control (p <.0001) significantly influenced this end point. Multivariate analysis revealed that gender (p =.0049), T stage (p <.0001), N stage (p <.0001), and locoregional control (p <.0001) significantly influenced cause-specific survival. CONCLUSIONS: The risk of distant metastases after definitive radiotherapy is 14% at 5 years and is significantly influenced by gender, T stage, N stage, nodal level, and locoregional control.