Loss of life expectancy due to colorectal cancer at national and subnational level in China, 2005-2020: a retrospective population-based study from China national mortality surveillance system

Background: Colorectal cancer was the fourth leading cause of cancer death in China in 2020, and mortality due to colorectal cancer increased in economically developed regions between 2005 and 2020. This study aimed to explore the temporal trends in loss of life expectancy due to colorectal cancer in China and all mainland provinces from 2005 to 2020. Methods: The mortality data were obtained from the China National Mortality Surveillance System (NMSS), which covers a population of more than 300 million people in 31 provincial-level administrations with provincial-level representativeness. Under-reporting rate was used to adjust for death rates from all cause and colorectal cancer. The demographic data were obtained from the National Bureau of Statistic. We used the abbreviated life table method to calculate life expectancy. Loss of life expectancy due to colorectal cancer was calculated as the life expectancy after excluding colorectal cancer deaths in the whole population by gender and provinces. Underlying cause of death coded as colorectal cancer based on the International Classification of Diseases, 10th edition (ICD-10) was used (C18.0-C18.9). The study was approved by the Ethics Committee of The National Center for Chronic and Noncommunicable Disease Control and Prevention. Findings: The loss of life expectancy due to colorectal cancer in China in 2020 was 0.15 years, slightly higher in men (0.154 years) than in women (0.147 years). Loss of life expectancy due to colorectal cancer is on an increasing trend between 2005 and 2020, for both genders, with a higher increase for men (0.03) than for women (0.02). The provinces with the highest loss of life expectancy due to colorectal cancer in 2020 were Beijing (0.30), Zhejiang (0.26), and Shanghai (0.26), and the lowest were Tibet (0.04), Hebei (0.09), and Henan (0.10). Among all 31 mainland provinces, 3 provinces (Hebei, Henan and Jiangxi) showed a decreasing trend for loss of life expectancy due to colorectal cancer. For the remaining provinces, Tianjin (96.97%), Fujian 80.28%), and Beijing (70.28%) had the highest increase in loss of life expectancy due to colorectal cancer during the study period. Interpretation: The loss of life expectancy due to colorectal cancer is increasing during 2005-2020, indicating it remains a major public health problem in China, particularly in economically developed provinces. The strengths of this study are the use of loss of life expectancy as the indicator to measure the burden caused by colorectal cancer and its temporal trend based on nationwide data. The limitation of this study is that we were unable to analyze the associated factors for the variations between different provinces.