I'd like to introduce our second speaker, Dr. Kituta Ashizawa, and he is a professor at Nagasaki University. Dr. Ashizawa will share Japan's experience implementing CT lung cancer screenings. Thank you, Mr. Chairman. Good morning. I'm Dr. Ashizawa from Nagasaki, Japan. So today I would like to talk about the current status of lung cancer screening in Japan. This slide shows a trend in mortality rate by cancer site in Japan. Lung cancer remains the leading cause of cancer deaths in Japan, as well as the Western countries. This slide shows a comparison of lung cancer mortality rate in Japan and the United States by smoking status. The risk of lung cancer death among smokers in Japan is lower than that, than half that in the United States. But conversely, the risk of lung cancer death among non-smokers is about 2.5 times higher than the United States. So in Japan, the risk of lung cancer among non-smokers cannot be ignored. In terms of the lung cancer screening, three large American National Cancer Institute-sponsored screening programs were performed using chest radiography and sputum analysis in the 1970s. According to the results of these randomness control trials, they have not shown a benefit in reducing lung cancer mortality in the second screening group. While four case control studies of screening with chest radiography in 1990 in Japan on population level were reported. These studies suggested chest radiography screening effectiveness, as indicated by lung cancer mortality reductions, of 28 to 60 percent. Therefore, chest radiography is recommended to perform as opportunistic screening as well as the population-based screening according to the current guidelines for lung cancer screening in Japan Ministry of Health, Labor, and Welfare from 2006. So this is a case of medially invasive adenocarcinoma of the lung detected in lung cancer screening by chest radiography. Here is the data of population-based cancer screening in Japan in 2015. Among eight million people participated in lung cancer screening by chest radiography annually, of which more than 80 percent are non-smokers. About 4,600 cases of lung cancer have been diagnosed. However, due to the low screening rate, only 4 percent of total incident cases in Japan are diagnosed by screening annually. So I will move on to the topic of rural CT screening. In Japan, CT screening for lung cancer was initiated first in the world, and several single-group cohort studies showed a high frequency of early-stage lung cancer. The percentage of rural CT screening detected stage 1 lung cancer ranged 77 to 100 percent. After initial results of rural CT screening for lung cancer were reported, rural CT screening for lung cancer has spread in medical check-up facilities as an opportunistic screening, and has provided increased opportunity to detect lung cancer in Japan. This slide shows a national survey of cancer screening for workplace. Various types of cancer screening are conducted, but 80 percent of the health insurance associations provide lung cancer screening, and the participation rate has reached 70 percent. As for what kind of examinations are conducted at workplace as lung cancer screening, 21 percent of the health insurance unions provide chest CT screening. So I will show you the results of the ecological time series of study of rural CT screening for lung cancer performed in Hitachi City, where the largest scale chest CT screening program for lung cancer has been introduced in Japan. For a total of more than 30,000 participants received the screening as of March 2009, 40 percent Hitachi residents aged 50 to 69 were estimated to have received the screening program. So during the third period, which correspond to four to eight years after the introduction of CT, a statistically significant 24 reduction in lung cancer mortality for men and women combined was found in Hitachi City. So this may suggest that wide implementation of CT screening can decrease lung cancer mortality at community level. So Dr. Inaba also performed the retrospective cohort study of screening for participating participants among Hitachi residents. The hazard ratio of the CT group to the chest radiograph group adjusted for gender, age, and smoking history was 0.49 for lung cancer mortality. Non-smokers and light smokers had a significantly lower lung cancer mortality. So despite of selection bias, in some extent, CT screening may be effective for non- or light smokers. So there are several internationally accepted guidelines available on the management of incidental pulmonary nodules detected on CT, such as Russian Society, LungLATS, and so on. So in January 2005, Pulmonary Nodule Management Committee of the Japanese Society for CT Screening published the Guidelines for Pulmonary Nodule Management, Version 1. This slide shows a schema of the guidelines, Version 6. Basically, this guideline consists of three steps, namely, Step 1, pick up pulmonary nodules. Step 2, classification of pulmonary nodules on C-sectional CT three months later. And Step 3, follow-up CT examination. So in Japan, this guideline is commonly used in actual situation. In Step 2, pulmonary nodules, more than six millimeter in diameter detected on load of CT screening are classified into three types, pure ground gas nodules, porcelain nodules, and solid nodules. So indications of diagnosis workup in Step 2 include the solid nodule more than 10 millimeter, sub-solid nodule more than 15 millimeter in diameter. For porcelain nodules less than 15 millimeter in diameter, indications of diagnosis workup is porcelain less than eight millimeter, based on the results of our two papers. In Step 3, follow-up CT intervals depends on the nodule type. Based on the result of our paper shown on this slide, interim recommendations for follow-up or sub-solid nodules are as follows. Porcelain nodules every six months, pure ground gas nodule every one year, or possibly every two years. So proven risks of load CT screening for lung cancer, such as overwork of readers, a large number of false positive nodules, overdiagnosis, and so on, are summarized on this slide. I'll discuss evidence of significant reduction of lung cancer rate. So NLST and NELSO study, which are the two largest randomized control trials of CT screening for heavy smokers, showed significant mortality reduction in lung cancer patients. But the efficacy of load CT screening for lung cancer in never or light smokers has not been established. I'll introduce an ongoing Japanese randomized control trial, JECC study, comparing load of CT screening to chest radiography screening in non or light smokers. Recruitment of all 27,000 participants aged 50 to 70 years who have non or light smokers has already finished in this study. Participants in chest radiography group received chest radiography annually, while the participant in CT group received two CT examinations at baseline and year six. They will be followed for 10 years, and lung cancer mortality will be compared between the two groups. So from 2006, load of CT screening has not been recommended to perform as a population-based screening from Japanese government, because the evidence of reduction of lung cancer mortality rate was insufficient. While load of CTs are accepted to perform as opportunistic screening with informed consent of the potential benefits, harm about the CT screening, the update of lung cancer screening guideline has begun. So in summary, based on Japanese guidelines, chest radiography is recommended to perform as opportunistic screening, as well as the population-based screening. Load of screening is accepted to perform as opportunistic screening with informed consent of potential benefits, harm, and current uncertainties about load of CT screening. And the detecting nodule should be followed up and managed according to the appropriate guidelines. In Japan, discussions regarding the implementation of load of CT screening for heavy smokers has just begun, mainly at academic conferences. We must consider how load of CT screening should be implemented as a population-based screening for heavy smokers. Thank you very much for your attention.

lung cancer screening

Nagasaki University

chest radiography

CT screenings

mortality rates