Changes in lung cancer incidence by sex and smoking status in China: a multicentre observational study

Abstract Background Lung cancer is traditionally more prevalent in elderly people, men, and smokers, and is usually diagnosed at an advanced stage. However, as low-dose CT (LDCT) lung cancer screening is increasingly popular in some regions of China, and since it might lead to the detection of more small-sized lung cancers, we hypothesised the spectrum of lung cancer might change. Methods This observational study included three datasets. The first dataset included LDCT lung cancer screening results for employees from five hospitals in different regions of China in 2012–17. The second dataset included lung cancer incidence and mortality from the Shanghai Cancer Registry in 2005–14. The third dataset included clinicopathologic data for patients with primary lung cancer undergoing surgical resection in the Fudan University Shanghai Cancer Center (FUSCC), Shanghai, in 2008–17. To characterise trends in lung cancer incidence over time, we calculated the average annual percent change (APC) using Joinpoint (version 4.1.1.3) by the National Cancer Institute. We used the Cochrane Armitage trend test to determine if the proportion of the young, female, non-smoking, or stage 0/IA patients increased over the years. This study was approved by the ethics committee of each participating institution. Findings LDCT screening detected lung cancer in 164 hospital employees with pathological confirmation. Of the hospital employees with lung cancer, a high proportion were female (81·7%), non-smokers (91·5%), younger than 55 years (58·5%), and had stage 0/IA cancer (93·3%). The proportion of hospital employees with lung cancer was 1·2% in women and 0·7% in men. In Shanghai, lung cancer incidence in women increased significantly (APC 5·50%, p=0·0008) from 17·6 cases per 100 000 in 2005 to 25·8 cases per 100 000 in 2014, while the incidence in men did not change significantly (p=0·1255). Incidence in women increased significantly in all the age subgroups between 30 and 64 years. Among 8355 patients with lung cancer undergoing surgery in FUSCC in 2008–17, the proportion of women (from 32·8% to 55·7%), non-smokers (from 43·9% to 68·5%), patients aged 40 years or younger (from 2·2% to 8·6%), and patients with stage 0/IA cancer (from 32·2% to 73·0%) increased significantly from 2008 to 2017. Interpretation We observed an increasing trend of young, female, non-smoking, and early-stage lung cancer in China, which is in contradictory to classical concepts and brings new challenges and opportunities to change clinical practice. Funding National Natural Science Foundation of China ( 81330056, 81572253, 81572264, 81772466, and 81702258 ) and Chinese Minister of Science and Technology grant ( 2016YFA0501800 and 2017YFA0505501 ).