Incidence trends and age distribution of colorectal cancer by subsite in Guangzhou, 2000-2011.

Introduction: Colorectal cancer (CRC) is the third most common cancer in China. The incidence of CRC has been increasing in recent years. The aim of this study was to explore the incidence trends and the age distribution of CRC by subsite in Guangzhou between 2000 and 2011.

Methods: A total of 22,432 incident cases of CRC between 2000 and 2011 from Guangzhou Cancer Registry were identified. Crude incidence and age-standardized rates (ASRs), using the Segi's world standard population, were calculated for CRC and CRC subsites. The incidence trend was analyzed and the annual percentage change (APC) in incidence was calculated by using JoinPoint software.

Results: The crude incidence increased significantly from 23.4/10(5) in 2000 to 37.4/10(5) in 2011 for males and from 20.9/10(5) to 30.5/10(5) for females. The ASRs of CRC incidence stabilized during the period of 2000-2011 for both males and females. The ages at the onset of CRC for both males and females during 2010-2011 were significantly higher compared with those during 2000-2002 (males: t = 1.95, P = 0.05; females: t = 6.03, P < 0.01). For males aged 50-64 years, the CRC incidence increased by 8.50% annually (P = 0.04) during 2000-2004 and by 1.68% annually (P = 0.03) during 2005-2011. For females aged 65 years and older, the CRC incidence increased by 5.77% annually (P = 0.03) during 2000-2004. There were no significant changes for the CRC incidences in males aged 49 and younger and 65 years and older and females aged 64 years and younger during 2000-2004, or for those in all females as well as males aged 49 years and younger and 65 years and older during 2005-2011. The percentage of colon cancer in all CRCs increased significantly for both males and females between the periods of 2000-2002 and 2010-2011. The ASRs of descending colon and sigmoid colon cancer incidences increased significantly for females during 2005-2011 (APC, 5.51% and 1.08%, respectively, both P < 0.05).

Conclusions: The crude incidence of CRC increased significantly between 2000 and 2011 because of the aging, whereas the ASRs kept stable. The percentage of colon cancer in all CRCs increased significantly. Further surveillance, research, and intervention are needed to identify the causes of these changes and to reduce the incidence and mortality of CRC.