Purpose: This study evaluated the effect of loco-regional control on incidence of distant metastases in patients with nasopharyngeal carcinoma.
Methods and materials: Retrospective analysis was performed on 1301 patients with nasopharyngeal carcinoma treated from 1976-1989 in our hospital. The effect of different prognostic indicators on distant metastases free survival (DMFS) was analyzed, including T stage, N stage, sex, and loco-regional control. The significance of loco-regional control in distant metastatic dissemination was further studied with period and subgroup analysis. Cox regression was performed to identify the independent prognostic variables.
Results: Patients with loco-regional relapse had significantly higher distant metastases rate than patients with loco-regional control (time-adjusted distant metastases rate at 5 years was 40.7% vs. 29.4%, p = 0.0012). By period analysis, the effect of loco-regional control on distant metastases was found to be significant in the first 2 years from diagnosis. Subgroup analysis showed that loco-regional relapse was associated with significantly higher distant metastases rate in patients with T1, N0, and N1 disease (p = 0.001, 0.001, 0.0226, respectively). The Cox regression model also confirmed loco-regional control as an independent prognostic indicator of distant metastases (p = 0.0001) besides T stage (p = 0.0006) and N stage (p = 0.0001).
Conclusion: Loco-regional relapse is a significant risk factor for development of distant metastases. Further effort should be made to improve loco-regional control and to eradicate distant metastases.