Emerging biomarkers for early detection of colon cancer
Published:Wednesday | March 20, 2024 | 12:07 AMKeisha Hill/Senior Gleaner Writer
COLORECTAL CANCER is a type of cancer that affects the colon (large intestine) or rectum. It is one of the most common types of cancer worldwide that can cause severe harm and death.
The risk of colorectal cancer increases with age and in most cases affect people over 50 years old. Common symptoms include diarrhoea, constipation, blood in the stool, abdominal pain, unexplained weight loss, fatigue, and low iron levels. Many people will not have symptoms in the early stages of the disease.
Colon cancer is the second-leading cause of cancer-related deaths worldwide. In 2020, more than 1.9 million new cases of colorectal cancer and more than 930,000 deaths due to colorectal cancer were estimated to have occurred worldwide.
The risk of colorectal cancer can be reduced by eating a healthy diet, staying physically active, not smoking tobacco and limiting alcohol. Regular screenings are crucial for early detection.
Diagnostic methods for colorectal cancer include physical examination, imaging (such as abdominal ultrasound, computed tomography scans, and magnetic resonance imaging), examination of the inside of the colon using colonoscopy or sigmoidoscopy, taking a sample of tissue (biopsy) for histopathology examination, and molecular testing to identify specific genetic mutations or biomarkers to guide the best treatment option.
According to Dr Dayna Kaye Taylor-Forbes, gastroenterologist, emerging biomarkers for early detection of colorectal cancer include fecal immunochemical test (FIT), guaiac-based fecal occult blood test (gFOBT) and multitarget stool DNA test with FIT testing.
The fecal immunochemical test is required annually and needs only one stool sample. There is no restriction of diet or medication to administer this test. “Both qualitative and quantitative FIT is available. The patient receives the kit and returns it within 24 hours. It is very convenient, so there is a high adherence level. A positive FIT requires a follow-up colonoscopy,” Dr Taylor-Forbes said.
The guaiac-based fecal occult blood test identifies haemoglobin by turning guaiac-impregnated paper blue as a result of a peroxide reaction. This test is performed annually, and is administered with the elimination of red meat for three days. Vitamin C of 250mg per day is also restricted for three days.
“Avoid NSAID for seven days, and stool should not be obtained from DRE. Three consecutive samples are required, and a positive test requires a colonoscopy,” Dr Taylor-Forbes said.
“The idea behind this test is that blood vessels at the surface of larger polyps or cancers are often fragile and easily damaged by passing stool. The damaged blood vessels usually release a small amount of blood into the stool, but only rarely is there enough bleeding to be visible in the stool. The FOBT is an easy way to determine whether there is blood in your stool, which could be the result of polyps or colorectal cancer,” she added.
This screening test is done with a kit that you can use in the privacy of your own home. Another important part of this kit, and test, is that it requires you to check more than one stool sample. Also, unlike some other screening tests (including colonoscopy), this one must be repeated every year.
The multitarget stool DNA with FIT, also called Cologuard, is an option for colorectal cancer screening and is recommended for use in average-risk individuals age 45 years and older.
“Patients collect a stool sample at home, send it to the manufacturer’s laboratory within one day, and the result is reported in approximately two weeks. Compared with FIT, sDNA-FIT has higher sensitivity but lower specificity for colorectal cancer, which translates to a higher false-positive rate,” Dr Taylor-Forbes said.
Retesting is recommended every one to three years, although the optimal testing interval has not yet been determined empirically.
Lifestyle changes and regular screening can help prevent colorectal cancer. These lifestyle changes include eating a healthy diet rich in fruits and vegetables, not smoking tobacco, keeping an active lifestyle, limiting alcohol consumption, and avoiding exposure to environmental risk factors.
People who suspect they may have colorectal cancer should speak to their doctor right away. Regular screening for colorectal cancer secondary prevention is the best way to catch the disease early. Treatments are more likely to cure the disease in the early stages. Studies have shown that screening can reduce both the incidence and mortality of colorectal cancer through early detection and removal of precancerous growths.
Dr Taylor-Forbes was one of the presenters at the Colon Cancer Medical Webinar put on by the Jamaica Cancer Society in association with Apex Radiology, Abbott Nutrition, A.A. Laquis (Jamaica) Limited, and Facey Commodity Company Limited.
SOURCE: World Health Organization, Jamaica Cancer Society