The Introduction of Low-Dose CT Imaging and Lung Cancer Overdiagnosis in Chinese Women

BACKGROUND: Overdiagnosis of lung cancer by low-dose CT (LDCT) screening has raised concerns globally. LDCT screening has been used widely in employee health examinations in China since 2011. RESEARCH QUESTION: Has the increasing use of LDCT in low-risk populations in China led to lung cancer overdiagnosis?STUDY DESIGN AND METHODS: A total of 34,152 incident cases of and 27,208 deaths resulting from lung cancer in a population of approximately 3 million were derived from the Cancer Surveillance of Shanghai between 2002 and 2017. Changes in stage-specific and histologic type-specific incidence and mortality and incidence rate ratio (IRR) relative to the base year 2002 or to the period 2002 through 2005 were calculated by sex and were used to evaluate potential overdiagnosisve of lung cancer.RESULTS: In men, both age-adjusted incidence of and mortality as a result of lung cancer decreased significantly up to 2008 and thereafter remained stable; in women, the incidence increased rapidly from 2011 (annual percentage change, 11.98%; 95% CI, 9.57%-14.45%), whereas the mortality declined persistently. The upward trend of incidence mainly was observed in lung adenocarcinoma in both sexes, with a sharper increase from 2012 through 2017. In men, the incidence of early-stage cancer increased 6.9 per 100,000 (95% CI, 5.1-8.7 per 100,000) and was accompanied by 5.5 per 100,000 (95% CI, -9.2 to -1.7 per 100,000) decline in late-stagecancer from 2002 through 2017. In women, early-stage incidence rose 16.1 per 100,000 (95% CI, 14.0-18.3 per 100,000), but no significant decline in late-stage cancer was found (absolute difference, -0.6 per 100,000; 95% CI, -2.8 to 1.7 per 100,000). The IRR was highest in most recent period and increased most in young women, mainly for early-stage cancer or lung adenocarcinoma.INTERPRETATION: The results provide evidence at a population level for lung cancer over -diagnosis in Chinese women resulting from increasing LDCT screening in the low-risk populations. Criteria for LDCT screening and management of screening-detected nodules need to be addressed fully for expanded application of LDCT screening in China.