Urban-rural disparities of loss of life expectancy due to lung cancer in China from 2005 to 2020: a nationwide study from China national mortality surveillance system

<h2>Abstract</h2><h3>Background</h3> Lung cancer remains the leading cancer type by mortality rate in China and most of its provinces. This study aims to explore the urban-rural disparities for years of life expectancy lost due to lung cancer in China from 2005 to 2020. <h3>Methods</h3> Data used for estimates of life expectancy were obtained from China National Mortality Surveillance System (NMSS) during 2005-2020. NMSS collects all deaths occurred both in hospitals and outside-of-hospitals in 605 counties/districts (209 in urban areas and 396 in rural areas) across all 31 provinces in mainland China with proved national and provincial representativeness. Demographic information, date of death and cause of death were recorded for all deceased cases. Underlying cause of death coded as C33-C34 based on the International Classification of Diseases, 10^th edition (ICD-10) was used for estimates of mortality rate of lung cancer. We used the abbreviated life table to calculate life expectancy. Loss of life expectancy due to lung cancer was calculated by subtracting the observed life expectancy in the population from the expected life expectancy without lung cancer death for each year. Loss of life expectancy due to lung cancer was compared between urban and rural areas and the secular trend of urban-rural disparity during 2005-2020 was explored. The study was approved by the Ethics Committee of The National Center for Chronic and Noncommunicable Disease Control and Prevention. <h3>Findings</h3> Loss of life expectancy related to lung cancer increased from 0.550 years in 2005 to 0.630 years in 2020, consistently higher in urban areas than in rural areas during the study period. Loss of life expectancy due to lung cancer in urban areas declined from 0.703 years in 2005 to 0.691 year in 2020. Whilst in rural areas, it increased from 0.472 years in 2005 to 0.595 years in 2020. The gap between urban and rural areas narrowed down from 0.231 years in 2005 to 0.096 years in 2020 and this converging trend was seen in both men and women. The loss of life expectancy due to lung cancer among men was higher in urban areas than that in rural areas in the past 15 years. However, the gap between the two groups is gradually narrowing, decreasing from 0.270 years in 2005 to 0.118 years in 2020. The gap between urban and rural areas among women also narrowed down, from 0.159 years in 2005 to 0.066 years in 2020. In 2020, the provinces with the highest loss of life expectancy due to lung cancer are Heilongjiang (0.944), Tianjin (0.929), Zhejiang and Chongqing (both 0.915) while the lowest was Xizang (0.138), Qinghai (0.353) and Xinjiang (0.370). <h3>Interpretation</h3> Although urban-rural disparities of loss of life expectancy due to lung cancer narrowed down from 2005 to 2020, attention should be paid to rural areas and more tailored prevention and intervention measures should be in place to avoid the increasing loss of life expectancy due to lung cancer in rural China.