Colorectal Cancer: How Lab Tests Can Spot It Early - Expert

Colorectal cancer affects the colon and rectum. It is one of the most common cancers in the world. Many people do not notice it for a long time because early stages may not show any symptoms.

The World Health Organisation (WHO) estimates that in 2022, there were 1.9 million new cases of colorectal cancer and over 900,000 deaths globally.

The WHO says symptoms can include blood in the stool, changes in bowel habits, abdominal pain, unexplained weight loss and fatigue.

Some people may not see warning signs. Screening can help find possible problems before the disease gets worse.

What happens before a diagnosis is confirmed?

Laboratory tests are key in this process. Medical laboratory scientists check samples to find out what is happening in a patient’s body.

Adedoye David, a medical laboratory scientist, told PT HEALTH WATCH that lab tests help in the investigation of colorectal cancer. This is done by examining biological samples like stool, blood, and tissue.

One test is the Faecal Occult Blood Test (FOBT). This test finds blood in stool that is not visible to the eye.

Another test is the Faecal Immunochemical Test (FIT). This test uses antibodies to check for human haemoglobin in stool.

These tests can help find people who may need more checks. But Mr David stressed that finding blood in stool does not mean a person has cancer.

“Stool-based tests are very important for detecting hidden blood in stool. It could be reliable if the test investigation is carried out using the right and standard operating procedures.

“But as much as it can be reliable in detecting hidden blood, it might not be totally reliable in the diagnosis of colorectal cancer,” he said.

If more investigation is needed, Mr David said a patient may be referred for procedures like colonoscopy. This helps find abnormal areas and take tissue samples for lab tests.

A biopsy can then show if the abnormal tissue is cancerous.

Why symptoms should not be ignored

It is important to understand the difference between screening and diagnosis. Colorectal cancer does not always show obvious symptoms.

A person who feels fine may not think testing is necessary. Someone who gets a negative stool test may feel they do not need to see a doctor.

Mr David said both of these ideas can be wrong.

He urged people to seek medical advice if they have ongoing symptoms. Waiting for symptoms to get worse is not a good idea.

He also advised people with a family history of colorectal cancer or long-term inflammatory bowel disease to talk to healthcare professionals. They should find out if they need earlier or more frequent screenings.

The WHO lists family history of colorectal cancer and certain inflammatory bowel diseases as factors that can raise a person’s risk.

Even though colorectal cancer is more common in older people, it is not only an issue for them. The WHO has also reported more cases among younger adults in many countries.

Screening is only useful when people can complete it

Getting people to take screening tests is not the only problem. The health system must also help when a test shows something unusual.

Evidence from Nigeria shows this issue.

A study in Nigeria with over 2,000 adults found that FIT screening could work. But researchers noted problems with follow-up colonoscopy after positive results.

This means that finding a possible issue is just one part of the process. Patients need access to more tests to understand what the abnormal result means and start treatment if needed.

Mr David mentioned limited facilities for important tests and the cost of services as major challenges for colorectal cancer testing in Nigeria.

For people who might already be unsure about testing, costs and availability can make early detection harder.

Mr David also encouraged Nigerians to overcome any embarrassment about providing stool samples for lab tests.

“There is nothing to be ashamed of producing a stool sample. It is just like any other medical sample and it is needed for us to carry out informed diagnosis,” he said.

In the end, a stool test is not a final answer on whether a person has cancer. It is just one step in a process to help health professionals see who needs more checks.

For Mr David, improving outcomes for colorectal cancer needs both public awareness and access to good lab and diagnostic services. This way, people can seek help early and any abnormal findings can be looked into properly.