Colorectal cancer screening looks for polyps and tumors in people who have no symptoms. In Spain the public program invites men and women aged 50 to 74 to take a fecal occult blood test every two years, and if the result is positive a colonoscopy follows. The extension up to age 74 was approved in April 2026 and the regions have five years to apply it, so some still only invite people up to 69.
What is colorectal cancer screening for?
To find and remove polyps before they turn into cancer, and to catch cancers that already exist at an early stage. Most colorectal cancers start from a polyp, a small growth that can turn malignant over the years. If the polyp is found and removed first, the cancer never develops. When what is found is already a cancer, screening usually catches it at an early stage, when it is most curable.
Colon cancer may cause no symptoms until it is fairly advanced. That is why screening is offered to people who feel well.
Who should be screened?
The program is designed for people at average risk: aged 50 to 74, with no symptoms and nothing in their history that raises the risk. Each Spanish region runs its own program, so how the invitation arrives and where the test is collected and returned varies. If you are in that age range and have not been invited, ask at your health center.
Who needs a colonoscopy without waiting for the program?
For some people a test every two years is not enough. They need their own assessment, usually with colonoscopy and sometimes starting before 50:
- People with relatives who have had colorectal cancer, especially first-degree relatives (parents, siblings, children), several relatives, or relatives diagnosed at a young age.
- People who have had polyps or colorectal cancer.
- People with inflammatory bowel disease, such as ulcerative colitis or Crohn's disease.
- People who have, or may have through their family, a hereditary syndrome such as Lynch syndrome or familial adenomatous polyposis.
These are the people we see in the high-risk clinic, where we decide with each of them the age to start, the test to use and how often to repeat it.
Someone who already has symptoms, such as blood in the stool, a change in bowel habits that does not go away or tiredness from anemia, does not need screening either. They need to see a doctor without waiting for the next invitation or for the test result.
How is the fecal occult blood test done?
At home, by collecting a small stool sample that is then handed in for analysis. The test detects amounts of blood that cannot be seen with the naked eye. The process is simple: you collect a small stool sample with the tube provided, following the instructions, and hand it in for analysis. It does not hurt.
If the result is negative, no blood has been found and the next test is in two years. A negative result does not cover what happens in between: if symptoms appear during those two years, see a doctor. Sometimes the sample cannot be analyzed, almost always because it was not collected properly, and the test has to be repeated.
What happens if the test is positive?
A positive result means traces of blood were found in the stool. It does not mean there is a cancer: the blood most often comes from benign polyps or hemorrhoids. A colonoscopy is needed to find out where it comes from, and it is important to have it. A positive result is not cleared up by repeating the test.
What is a colonoscopy like?
A flexible tube with a camera is passed through the anus to view the rectum and the whole colon. It is usually done under sedation, so the patient is not aware of it. In the days before, you follow a diet and take a preparation that cleans out the bowel, because lesions cannot be seen properly if stool remains.
During the colonoscopy polyps can be removed on the spot and biopsies taken from any suspicious lesion. A cancer diagnosis is only confirmed by analyzing those samples. If it is confirmed, the specialist team decides what further tests are needed and proposes treatment.
Fecal occult blood test or straight to colonoscopy?
Both are valid screening tests. The Spanish public program uses the fecal occult blood test, which is done at home with no preparation, and keeps colonoscopy for positive results. Colonoscopy looks directly at the whole colon and removes polyps on the spot, but it needs bowel preparation and sedation.
For people at high risk the recommended test is usually colonoscopy. For everyone else, what matters is to be screened with the test that applies and to repeat it when due.
What if I live outside Spain?
Ages and tests vary by country. In the United States, for example, the U.S. Preventive Services Task Force (USPSTF) has recommended starting at 45 since 2021. In Latin America programs vary from country to country. If you are unsure when to start, ask your doctor, especially if there is a family history.
Frequently asked questions
At what age is colorectal cancer screening done in Spain?
From 50 to 74 in people with no symptoms or risk factors. The extension up to 74 dates from April 2026 and the regions have five years to apply it, so in some the program still ends at 69.
How often should the fecal occult blood test be repeated?
Every two years if the result is negative. If symptoms appear before the next test is due, see a doctor without waiting.
If the test is positive, do I have cancer?
Not necessarily. The blood most often comes from benign polyps or hemorrhoids. A colonoscopy is needed to find out, and it should not be put off.
I have a relative with colon cancer. Is the program enough for me?
It depends on who the relative is, how many relatives are affected and how old they were at diagnosis. With a first-degree relative or several affected relatives, a specific assessment is usual, with colonoscopy and often starting before 50.
I have blood in my stool. Should I wait for the test?
No. Screening is for people without symptoms. If you already notice blood, changes in bowel habits or unexplained tiredness, see your doctor.
Does a colonoscopy hurt?
It is usually done under sedation, so you do not feel it. For most people the hardest part is the bowel preparation in the days before.
References
- Spanish Ministry of Health. Colorectal cancer screening program: general information (in Spanish; target population 50 to 74 under Order SND/356/2026).
- Spanish Ministry of Health. Colorectal cancer screening program: frequently asked questions (in Spanish).
- U.S. Preventive Services Task Force. Colorectal Cancer: Screening (2021).
This information is for general guidance and does not replace an assessment by your doctor.