Lung Cancer Screening for Smokers in Japan (2026): Age 40+, and the "600" Smoking Index Rule
Table of contents
Scope of this article
This is a third-party explainer covering what the public program says: who is eligible, how often, and which test items apply. It does not assess what screening means medically, what any health effect might be, or whether any individual should be screened. Municipalities are the bodies that actually run these screenings, and the upper age limit, out-of-pocket cost, timing, application method and participating clinics are all set locally. Always confirm with your own city or ward office.
What the guideline specifies for lung cancer screening
- Target group: age 40 and over
- Interval: once a year
- Standard test items: interview (monshin) and chest X-ray
- Additional item: sputum cytology for people, as a rule aged 50 and over, with a smoking index of 600 or more
All of the above comes from the MHLW guideline (https://www.mhlw.go.jp/content/10900000/001471911.pdf). There is no separate "smokers-only" screening program in Japan; instead, the test items within the general resident screening change according to smoking history.
How the smoking index is calculated
The smoking index is simply cigarettes per day multiplied by years of smoking. Twenty a day for 30 years is 20 x 30 = 600, which meets the threshold. Ten a day for 60 years is also 600. Fifteen a day for 30 years is 450, below the threshold, while 15 a day for 40 years reaches 600. Critically, the condition includes former smokers — people who have already quit are still counted on the basis of their past smoking.
Why the interview answers matter
The smoking index is calculated from the number of cigarettes per day and the number of years you state during the interview. In other words, your answers determine whether the sputum cytology item applies to you. Under-reporting, or skipping the question because you have already quit, can mean a test item that would otherwise apply is not carried out. This is a point about how the program decides which tests to run — nothing more. State the facts as they are.
How to get screened
Municipalities usually announce screening through a mailed voucher or leaflet, the local newsletter, or the city website, and offer either group screening on set dates at set venues, individual screening at designated clinics, or both. Deadlines, cost and what to bring differ by municipality. Separately, an employer health check or a health insurance society programme may include a chest X-ray; eligibility, test items and cost can differ from the municipal route. Ask your employer's HR department or your health insurance society what is included. This article does not advise which route to choose.
Screening methods are being reviewed (2025)
In 2025 the National Cancer Center Japan published the fiscal 2025 edition of its guideline on lung cancer screening based on effectiveness evaluation, and a review of screening methods — including consideration of low-dose CT for heavy smokers — is under way (source: https://www.ncc.go.jp/jp/information/pr_release/2025/0425/index.html). When and how this is reflected in municipal screening depends on each municipality. Because the content of screening is under review, check your municipality's latest information before you go.
Related information
Japan's public health insurance can cover smoking cessation treatment under certain conditions — see our guide to smoking cessation clinics and insurance coverage. For where you may legally smoke, see the revised Health Promotion Act explained, and find designated smoking areas on the MottoSuitai map.
Disclaimer
This article summarises the framework of a public program as of 31 July 2026, based on MHLW and National Cancer Center Japan published information. Operational details are set by each municipality and screening methods are under review. This article introduces public programs and general information only; it is not medical advice and not a solicitation for insurance or any contract. For individual decisions, please consult a professional or the relevant official desk.
Frequently Asked Questions
Q.From what age can I receive municipal lung cancer screening in Japan?
A.The MHLW guideline sets the target group at age 40 and over, with an interval of once a year (source: https://www.mhlw.go.jp/content/10900000/001471911.pdf). Upper age limits and out-of-pocket costs are decided by each municipality, so check your local information.
Q.How is the smoking index of 600 calculated?
A.Cigarettes per day multiplied by years of smoking. Twenty a day for 30 years equals 600 and meets the threshold. The guideline provides sputum cytology for people, as a rule aged 50 and over, whose index is 600 or more.
Q.Does the rule apply if I have already quit smoking?
A.The smoking-index condition includes people who used to smoke. Report your past number of cigarettes per day and years of smoking accurately during the interview regardless of whether you currently smoke. Which tests are actually performed depends on the municipality and the screening provider.
Q.Is the content of lung cancer screening changing?
A.In 2025 the National Cancer Center Japan published the fiscal 2025 edition of its lung cancer screening guideline and a review of screening methods is under way, including consideration of low-dose CT for heavy smokers. Because of this, check your municipality's latest information before you go.