"It was just tiredness". That is how a 52-year-old man described the first signs he ignored for months. A teacher, active and with no known history of cancer, he believed that the change in bowel function was a consequence of stress from his routine. He had no severe pain, saw no obvious blood in his stools and continued working normally.

During a routine appointment at the Basic Health Unit, the doctor suggested a simple test: the FIT, an acronym for Faecal Immunochemical Test. The result came back positive. After colonoscopy, an advanced polyp was discovered in the intestine — a lesion that could have developed into cancer in the coming years. The problem was removed before that could happen.

Cases like this help explain why the FIT has been gaining ground in colorectal cancer screening strategies in the NHS and in various countries.

What is the FIT?

The FIT (Faecal Immunochemical Test) is an examination that detects small amounts of occult blood in stools, invisible to the naked eye. Unlike older occult blood tests, it uses specific antibodies to identify human blood from the large intestine.

In practice, the patient collects a small sample of stools at home and sends it for laboratory analysis.

The main objective is to identify early signs of intestinal changes even before symptoms appear.

Does the FIT only detect cancer?

No.

Although it is best known for helping with early detection of colorectal cancer, the test can also identify other changes that cause intestinal bleeding, such as:

  • intestinal polyps;

  • adenomas (precursor lesions of cancer);

  • diverticulosis;

  • inflammatory bowel disease;

  • haemorrhoids;

  • anal fissures;

  • colitis.

Therefore, a positive FIT does not necessarily mean cancer. It only indicates that there is intestinal bleeding that needs to be investigated.

Which cancer does the test help to detect?

The main focus is colorectal cancer, which affects:

  • colon;

  • rectum;

  • final part of the large intestine.

This is one of the cancers growing most rapidly in Brazil and worldwide.

According to the National Cancer Institute (INCA), Brazil should register approximately 45,630 new cases of colorectal cancer per year in the current three-year period, with approximately 21,970 cases in men and 23,660 in women.

Colorectal cancer is already among the most frequent cancers in the country, especially in the South and Southeast regions.

Who should have the FIT?

The test is most indicated for asymptomatic people with average risk, mainly from ages 45 to 50 onwards, depending on the screening strategy adopted by the health service.

Both men and women can have the test.

Generally speaking:

People without symptoms and without risk factors

  • screening usually starts between 45 and 50 years of age;

  • the FIT can be performed periodically, usually annually or biennially, according to the protocol adopted.

People with symptoms

Even below the screening age, the test can be requested when there is:

  • blood in stools;

  • persistent change in bowel habit;

  • unexplained weight loss;

  • anaemia;

  • persistent abdominal pain;

  • sensation of incomplete evacuation;

  • significant family history.

In these cases, colonoscopy is often necessary regardless of the FIT result.

Does the FIT replace colonoscopy?

Not completely.

The FIT is considered a screening and surveillance test. It helps select patients who need further investigation.

When the result is positive, the next step is normally colonoscopy.

The main advantage of the FIT is that it is:

  • simple;

  • non-invasive;

  • painless;

  • cheaper;

  • accessible;

  • easy to repeat periodically.

Colonoscopy, on the other hand, remains the most comprehensive test because it allows direct visualisation of the intestine and removal of polyps during the procedure.

What are the risk factors for bowel cancer?

The main factors associated with colorectal cancer include:

  • age over 50 years;

  • obesity;

  • sedentary lifestyle;

  • smoking;

  • frequent alcohol consumption;

  • diet rich in processed meats;

  • low fibre intake;

  • family history;

  • inflammatory bowel diseases.

The increase in sedentary lifestyle, obesity and ultra-processed food is concerning specialists because it is raising the incidence of this cancer in younger adults.

What are the symptoms that deserve attention?

Bowel cancer can remain silent for years.

When symptoms appear, the most common include:

  • blood in stools;

  • persistent diarrhoea or constipation;

  • change in the shape of stools;

  • abdominal pain;

  • anaemia;

  • unexplained weight loss;

  • frequent tiredness;

  • sensation of incomplete evacuation.

The problem is that many patients only seek help when the disease is already in more advanced stages.

Why is early detection so important?

When identified early, colorectal cancer has high chances of cure.

Furthermore, many cases can be prevented even before cancer appears, through the removal of intestinal polyps identified in tests.

Specialists also warn that late diagnosis significantly increases treatment costs for the NHS and reduces the chances of therapeutic success.

Does the NHS offer the test?

Access may vary depending on the region, local availability and screening programmes implemented by local authorities and regional health services.

In recent years, the FIT has received greater attention precisely because it shows good population screening capacity at lower cost than universal colonoscopy strategies.

The trend is for the test to be increasingly incorporated into public policies for colorectal cancer prevention.

What can be done to reduce the risk?

Some measures help prevent the disease:

  • maintain a diet rich in fibre;

  • consume fruit, vegetables and pulses;

  • reduce processed meats;

  • practise physical activity;

  • control weight;

  • avoid smoking;

  • reduce alcohol;

  • have preventive tests at the recommended age.

When should I see a doctor?

Any persistent bowel change deserves medical evaluation, especially after age 45.

Even people without symptoms may need to start preventive screening depending on age and family history.

Early diagnosis is still one of the most important tools for reducing deaths from bowel cancer.

This content is exclusively informational in nature and does not replace medical consultation, individualised assessment or specialist professional care. In case of symptoms or doubts, seek health care.

Dr. Rebeca Soares Andrade CRM-GO 39335