Over the past year, 50.9% of Japanese men and 46.2% of women got screened for colorectal cancer. That comes from Japan’s Ministry of Health, Labour and Welfare, in its 2025 Comprehensive Survey of Living Conditions (published July 15, 2026). Flip it around and about half of men, and a bit more than half of women, did not get screened.
People have their reasons. But for this particular test, we have a trial that measured what it does.
A randomized trial that ran for 30 years
The study started in Minnesota in 1976. It enrolled 46,551 people and split them into three groups: stool blood testing every year, every other year, or no screening. Researchers followed them for 30 years.
Deaths from colorectal cancer were 32% lower in the annual group and 22% lower in the every-other-year group (Shaukat A et al. N Engl J Med. 2013;369(12):1106-1114).
Because people were assigned by chance, the usual objection doesn’t apply here. In observational studies, screening can look good simply because healthier, more health-conscious people are the ones who show up. A randomized trial sidesteps that.
Notice the gap between yearly and every-other-year, too. Ten percentage points.
Japan’s guideline: age 40 and up, once a year
Under the Ministry’s guidelines for cancer screening, colorectal screening means a fecal occult blood test once a year for anyone 40 or older. You can get it through your municipality’s community screening program or through a workplace checkup. Out-of-pocket cost varies by city, so check with yours.
The test itself is just stool samples from two days.
A positive result is where it really starts
The test looks for tiny amounts of blood in stool. Positive doesn’t mean you have cancer. It means someone needs to look inside your colon. Hemorrhoids and polyps can also turn it positive.
The weak point is people who test positive and never follow up with a colonoscopy or other detailed exam. Screening only works when the whole chain is connected: test, follow-up exam, and treatment if needed. The mortality drop in the trial above includes positives going on to colonoscopy. Dropping off a stool sample and stopping there uses half the system.
Other cancer screenings, same picture
The same 2025 survey found past-year screening rates of 48.8% for men and 38.3% for women for stomach cancer, and 55.2% for men and 49.5% for women for lung cancer. Over the past two years, 51.0% of women had breast cancer screening and 46.1% had cervical cancer screening. None of them reach the national target of 60%.
What the numbers can’t tell you
That trial was American, and its participants were 50 to 80 years old when recruited in the 1970s. The test used was an older chemical method, different from the immunochemical test used in Japan’s programs today. So it doesn’t carry over to today’s Japanese seniors automatically. Screening also has downsides: false positives that send healthy people for follow-up exams, and rare complications from colonoscopy itself.
There is no single age at which to stop. At 80 or 90, the answer depends on your other health conditions, your physical strength, and whether you would actually want treatment if something were found. That has to be decided case by case. Whether to keep screening and whether to have a colonoscopy are questions to bring to your regular doctor.
If you already have symptoms such as blood in the stool, narrower stools, or alternating diarrhea and constipation, don’t wait for a screening slot. See a doctor soon. Screening is designed for people with no symptoms.
Staying out of the “other half”
Japan’s Fourth Basic Plan to Promote Cancer Control sets a 60% target for cancer screening participation. Right now the country falls short of it.
Screening notices are the kind of mail that sits unopened on a desk. If one came this year, go find it.
My book Walking to 110 collects what I’ve learned about Japan’s longevity habits. The Kindle edition is here. Next Thursday: a look at some everyday tools.
References
- Shaukat A, Mongin SJ, Geisser MS, et al. Long-term mortality after screening for colorectal cancer. N Engl J Med. 2013;369(12):1106-1114.
- Ministry of Health, Labour and Welfare (Japan). 2025 Comprehensive Survey of Living Conditions (published July 15, 2026).
- Ministry of Health, Labour and Welfare (Japan). Guidelines for Cancer Prevention Health Education and Cancer Screening.
- Ministry of Health, Labour and Welfare (Japan). Fourth Basic Plan to Promote Cancer Control (March 2023).