Time trends and age–period–cohort analyses on incidence rates of nasopharyngeal carcinoma during 1993–2007 in Wuhan, China

Abstract 

Background: Declines in incidence rates of nasopharyngeal carcinoma (NPC) were observed in Hong Kong and Taiwan but not other high-risk regions in China, while evidences from low-risk regions in China are still lacking. This study aimed to examine the time trends (1993–2007) of NPC in Wuhan (a low-risk region) and assess the birth cohort and calendar period effects on the observed temporal trends. Method: Using data from Wuhan Cancer Registry, age-standardized annual incidence rates of NPC were calculated by the direct method using the WHO World Standard Population (2000) as the reference. Trend in incidence rates of NPC during 1993–2007 was evaluated. Age–period–cohort models were also applied to assess the effects of age, calendar time and birth cohort on the observed temporal trends. Results: A total of 1685 new NPC cases (1210 males and 475 females) were diagnosed during 1993–2007 in Wuhan. The annual percentage change in incidence rates of NPC were 0.15% (95% confidence interval: −3.88% to 4.34%) for males and −1.17% (95% confidence interval: −4.85% to 2.66%) for females. No obvious cohort or period effect on the incidence rates of NPC was observed. Conclusion: The incidence rates of NPC remained stable during 1993–2007 in Wuhan, a low-risk region in China.

Keywords: Nasopharyngeal carcinoma, Incidence, Time trend, Age–period–cohort analysis