Objectives: The effect of ethnicity on nasopharyngeal cancer (NPC) outcomes is unclear. This retrospective analysis examines survival and the impact of concurrent chemoradiation (chemoRT) among Asian and non-Asian patients.
Methods: Subjects included 380 consecutive patients with NPC treated at a Canadian institution from 2000 to 2009. Five-year Kaplan-Meier progression-free survival (PFS), disease-specific survival (DSS), and overall survival (OS) were compared between Asian (n=279) and non-Asian (n=101) subjects. Multivariable analysis was performed using Cox regression modeling. Two-variable interaction terms with concurrent chemoRT were used to examine whether concurrent chemoRT conferred different effects among subgroups.
Results: Asian subjects presented with earlier stage (P=0.005), were younger, had better performance status, and were less likely smokers (all P<0.001). Survival among Asian versus non-Asian subjects with stage I/II NPC were: PFS 68% versus 59% (P=0.04), DSS 87% versus 77% (P=0.08), and OS 84% versus 74% (P=0.003). Corresponding rates with stage III/IVA/IVB disease were PFS 49% versus 42% (P=0.12), DSS 72% versus 46% (P=0.001), and OS 70% versus 44% (P<0.001). On multivariable analysis, Asian ethnicity, age below 65 years, ECOG performance status 0-1, early stage, staging MRI use, and concurrent chemoRT were associated with improved DSS and OS (P<0.05). On testing interactions with concurrent chemoRT, Asian versus non-Asian ethnicity was significant (hazard ratio 3.9), suggesting that concurrent chemoRT conferred more benefit among non-Asian compared with Asian subjects.
Conclusions: In this population-based study, Asian ethnicity was associated with improved DSS and OS. Concurrent chemoRT conferred more benefit among non-Asian compared with Asian subjects.
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