Abstract
PURPOSE: We aimed to develop and prospectively validate a risk score model to guide individualized concurrent chemoradiotherapy (CCRT) for patients with stage II nasopharyngeal carcinoma (NPC) in intensity-modulated radiotherapy (IMRT) era. MATERIALS AND METHODS: In total, 1220 patients who received CCRT or IMRT alone were enrolled in this study, including a training cohort (n = 719), a validation cohort (n = 307), and a prospective test cohort (n = 194). Patients were stratified into different risk groups by a risk score model based on independent prognostic factors, which were developed in the training cohort. Survival rates were compared by the log-rank test. The validation and prospective test cohorts were used for validation. RESULTS: Total tumor volume, Epstein-Barr virus DNA, and lactate dehydrogenase were independent risk factors for failure-free survival (FFS, all p < 0.05). A risk score model based on these three risk factors was developed to classify patients into low-risk group (no risk factor, n = 337) and high-risk group (one or more factors, n = 382) in the training cohort. In the high-risk group, CCRT had better survival rates than IMRT alone (5-year FFS: 82.6% vs. 74.0%, p = 0.028). However, there was no survival difference between CCRT and IMRT alone either in the whole training cohort (p = 0.15) or in the low-risk group (p = 0.15). The results were verified in the validation and prospective test cohorts. CONCLUSION: A risk score model was developed and prospectively validated to precisely select high-risk stage II NPC patients who can benefit from CCRT, and thus guided individualized treatment in IMRT era.