What gastrointestinal screening covers
Gastrointestinal (GI) screening looks for early cancers and the changes that come before them in the digestive tract. Two cancers drive most of it: colorectal cancer in the large bowel, and stomach cancer. Both are among the leading causes of cancer death worldwide, and both can grow for years without symptoms.
Why early detection matters
Most colorectal cancers begin as a polyp, a small growth on the bowel lining. Only some polyps ever become cancer, and it takes years. Removing them along the way lowers the risk of colorectal cancer later.
Risk factors that matter
These raise the risk of GI cancers:
- Age — colorectal screening starts at 45 in both Taiwan and the US
- A family history of colorectal cancer, which can mean starting earlier
- H. pylori, a common, treatable stomach infection linked to stomach cancer
- Smoking, and a diet high in processed or salted foods and low in fiber
How it's screened
| Program | Colorectal | Stomach |
|---|---|---|
| Taiwan (HPA) | Stool test (FIT) every 2 years at 45–74; at 40–44 every 2 years if a parent, child or sibling has had colorectal cancer | One-time H. pylori stool test at 45–74; no population gastroscopy program |
| US (USPSTF 2021) | Ages 45–75, by stool test, colonoscopy or other options | No US screening recommendation |
| Korea | Not covered here | Gastroscopy or barium X-ray every 2 years from 40 |
| Japan | Not covered here | Gastroscopy or barium X-ray from 50 |
- Show the lining of the large bowel, or of the esophagus and stomach
- Remove many polyps, and take biopsies, including for H. pylori
- See every polyp. A 2019 meta-analysis found about 26% of adenomas were missed on a first pass. A later repeat colonoscopy covers some of that gap.
- Reach most of the small intestine. A gastroenterologist uses capsule endoscopy when that matters.
- See the liver, pancreas or kidneys. An abdominal ultrasound images them when a clinician asks.
Colonoscopy carries small risks: in a 2016 meta-analysis, bowel perforation in about 0.5 and bleeding in about 2.6 per 1,000 exams. The gastroscopy and colonoscopy page covers prep, sedation and safety. After sedation you should not drive for 24 hours.
Lowering your risk, and what to do now
Not smoking, keeping alcohol modest, and eating more fiber with less processed meat all help. Treating an H. pylori infection lowers stomach-cancer risk. After polyps are removed, your gastroenterologist sets the next interval from their number, size and type.
- Heavy bleeding from the bowel, vomiting blood, or black stools with fainting: In Taiwan call 119 (the local equivalent of 911).
- Blood in the stool, a lasting change in bowel habits, trouble swallowing or unexplained weight loss: see a doctor soon. That is diagnosis, not screening.
- No symptoms: match yourself to the table; Taiwan's funded tests are for people with National Health Insurance who meet the criteria. A positive FIT should be followed by a diagnostic colonoscopy.
