Relapse patterns in WHO 2/3 nasopharyngeal cancer: Is there a difference between ethnic Asian vs. non-Asian patients?

Abstract

The purpose of this study was to assess whether ethnicity is an independent prognostic factor in patients with World Health Organization (WHO) type 2 or 3 nasopharyngeal carcinoma (NPC). Specifically, we examined the patterns of relapse observed in patients classified as "Asian" (born in southern China or southeast Asia) or "non-Asian" (born in Australia, Europe, the Middle East, or the Pacific Islands). All patients planned for radical treatment at the Peter MacCallum Cancer Centre from April 1985 to December 1999 were included in this study. Pathology was reviewed to confirm WHO type 2 or 3 NPC. Patients were staged using the 1997 International Union Against Cancer (UICC) criteria. Mean potential follow-up time was 9.6 years (range, 1.0-18.5 years) There were 158 patients: 86 Asian and 72 non-Asian. Stage groupings were: I--12 patients; II--32 patients; III--59 patients; and IV--55 patients. A staging computerized tomography was performed in 121 patients, and 53 (34%) also had a staging magnetic resonance imaging (MRI). The Asian patients had significantly more women, more patients aged <45, and more with performance status 0 than the non-Asians. Other putative prognostic factors were not significantly different between the groups. The 5-year rates for freedom from local recurrence (FLR), failure-free survival (FFS), and overall survival (OS) for Asian and non-Asian patients were 74% vs. 82%, 61% vs. 55%, and 75% vs. 63%, respectively. Corresponding 10-year figures were: 62% vs. 82%, 43% vs. 48%, and 58% vs. 49%, respectively. Multifactor analysis showed stage and the use of MRI for staging to be significant prognostic factors for all three endpoints. Age was also significant for FFS and OS. There were no significant differences in FFS or OS between Asian and non-Asian patients. However, the FLR interval was significantly worse in the Asian group (hazard ratio [HR], 2.37; 95% confidence interval [CI], 1.11-5.06), whereas duration of freedom from distant metastasis tended to be better (HR, 0.71; 95% CI, 0.33-1.53). Although this study provides no evidence that race is an independent prognostic factor for overall survival in patients with WHO 2/3 NPC, it does suggest that relapse patterns may vary, with a higher rate of late primary failures (offset by a lower rate of distant failure) in the Asian population. Further confirmatory studies with larger patient cohorts are indicated.