Patterns of Failure and Survival Trends Of 720 Patients with Stage I Nasopharyngeal Carcinoma Diagnosed from 1990-2012: A Large-scale Retrospective Cohort Study

Objectives:To evaluate the patterns of failure and survival trends of patients with stage I nasopharyngeal carcinoma (NPC) treated with radiotherapy alone over the last 20 years. Materials and Methods:A retrospective cohort study was conducted on 720 patients with stage I NPC who were treated with curative two-dimensional radiotherapy (2DRT), three-dimensional conformal radiotherapy (3DRT), or intensity-modulated radiotherapy (IMRT) between January 1990 and December 2012. The patients were categorized into four calendar periods (1990-1996, 1997-2002, 2003-2007, and 2008-2012) and four age subgroups (18-39, 40-49, 50-59, and >60). We computed overall survival (OS), progression free survival (PFS), locoregional relapse free survival (LRFS) and distant metastasis free survival (DMFS) as measures of patient survival. Results:After a median follow-up period of 105 months (range 1-280 months), we observed the increasing trends in survival and disease control. The 3-, 5-, and 7-year OS rates increased from 97.0%, 86.7%, and 81.7% in the first calendar period (1990-1996) to 100%, 99.3%, and 98.0% in the last calendar period (2008-2012), respectively (P<0.001). Additionally, significant increasing trends could be seen in the PFS and LRFS during the four calendar periods. In the subgroup analysis, the OS, PFS and LRFS in patients diagnosed older than 40 years had greater improvement than the younger patients. However, the rate of distant metastasis was stable and relatively low, as the 5-year distant metastasis rate ranged from 0.2%-2.5% among the four calendar periods. Conclusion:The survival rates in patients with stage I NPC showed increasing trends from 1990 to 2012. The advances of radiotherapy provided excellent locoregional control and enhanced overall survival, and in particular, the IMRT decreased locoregional relapse.