COVID-19 reduced the detection of lung cancer in first-time visitors, but not in repeated visitors in annual lung cancer screening.
Authors: Kimura Tatsuo , Fukumoto Shinya , Nakano Akemi , Fujii Hideki , Nadatani Yuji , Takashima Shingo , Nishii Yuko , Suzumura Tomohiro , Ageshio Naomi , Watanabe Toshio 
Published: June 2022

e24041 Background: Chest X ray (CXR) has been the most common screen procedure for detection of lung cancer. We have shown that there is a profit to repeated visitors to the same facility for the lung cancer detection screening (Kimura T. Health Prim Car, 2021). Declaration of Emergency by Japan government in response to the COVID-19 pandemic and subsequent changes made to healthcare provision impacted people's abilities to effectively manage their health condition. The hypothesis was that many people would be reluctant to visit health checkup centers, and that opportunities for detection of cancers would decrease. Methods: Our clinic “MedCity21” is a university outpatient clinic to undergo a complete medical checkup in private health screening program. The visitors with abnormalities detected in CXR were announced by call request and invited to our specialty clinic for chest CT scan as further examination. Per year from 2018 to 2021, we examined the varieties of abnormal shadows by CXR and CT scans and compared the differences between the repeated and the first-time visitors using the chi-square tests and one-way ANOVA. We determined 2018 and 2019 to be before COVID-19 and 2020 and 2021 to be during COVID-19. We have been checking for previous COVID-19, and those with previous COVID-19 can be seen after 4 weeks of recovery. Results: From 2018 to 2021, in order, there were 12540,13690, 12070, and 13409 visitors of which 45.0%, 42.5%, 32.1%, and 29.2% were first-time visitors, respectively. There was a significant decrease of first-time visitors during COVID-19 compared to before COVID-19 (p = 0.0454). From 2018 to 2021, the CXR abnormalities requiring further examinations were 2.7%, 2.4%, 2.4%, and 2.3%, of which 2.1% and 3.4% were repeated and first-time visitors, 1.8% and 3.2%, 1.8% and 3.8%, and 1.5% and 4.0%, respectively. Each year, the detection rate was significantly lower for repeated comparing to first-time visitors (p < 0.01). The CT confirmation revealed that CXR abnormalities in repeated visitors were diagnosed with different variations compared to those of first-time visitors. Repeated visitors had a significantly lower proportion of old inflammatory changes than first-time visitors. This distribution is consistent with our previous report. It should be noted that there were no lung cancer patients in first-time visitors, on the contrary, there were 3 confirmed lung cancer in repeated visitors in 2021. Conclusions: There was a significant decrease of first-time visitors during COVID-19 compared to before COVID-19, but the rate of decrease was not as high as expected. The repeated visitors had significantly lower rate of CXR abnormalities detection, but higher detection of lung cancer. The number of people with previous COVID-19 will continue to increase. If the facility has adequate infection control measures in place, it is recommended that medical checkups be conducted annually.