Overdiagnosis of lung cancer in Chinese populations

Abstract Background Low-dose computed tomography (LDCT) has been widely-used in employee health examinations in China since 2011. This study was designed based on the Cancer Surveillance data to quantify the overdiagnosis of lung cancer due to the introduction of LDCT in Chinese populations. Methods This registry-based cohort study included 46,978 incident cases and 34,475 deaths of lung cancer from Pudong New Area of Shanghai, China, during 2002-2020. We calculated the age-standardized rates (ASR) and average annual changes (AAC) of mortality and overall, stage-specific and histological type-specific incidence by sex to evaluate the potential overdiagnosis of lung cancer. We further estimated the numbers and proportions of lung cancer cases attributable to overdiagnosis by sex and period based on the comparison between the shape of the age-specific curves with that prior to the introduction of LDCT in the populations. Results The ASR of incidence of lung cancer increased rapidly since 2011 in both men (AAC: 1.90%; 95%CI: 0.87, 2.92) and women (AAC: 4.40%; 95%CI: 3.19, 5.62), whereas the ASR of mortality declined persistently, with AAC of -0.12% (-0.64, 0.39) in men and -0.19% (-0.47, 0.09) in women. The upward trends in incidence were mainly observed in women, for early-stage cancer and for lung adenocarcinoma. Overall, the overdiagnosis rate of lung cancer grew from 22% in 2011-2015 to 50% in 2016-2020 in women. Further analysis demonstrated elevated numbers (proportions) of lung adenocarcinoma cases attributable to overdiagnosis, which increased from 182 (8%) in 2011-2015 to 827(22%) in 2016-2020 in men, and from 1,842 (85%) to 4,171 (89%) in women. Conclusions This registry-based cohort study observed considerable and increasing overdiagnosis of lung adenocarcinoma in Chinese men and women. Guideline is urgently needed to maximize the benefits of LDCT screening and reduce the potential overdiagnosis of lung cancer in the populations. Key messages • The secular trends in incidence and mortality of lung cancer in Chinese populations demonstrated the overdiagnosis since 2011, when the LDCT was used as a part of staff health examination in China. • Overdiagnosis of lung cancer in Chinese populations increased incrementally over time and was mainly observed among women.