Colorectal cancer: Know the 9 tests used to diagnose it

Colorectal cancer or colon cancer changes and grows out of control. Along with physical examination, here are 9 tests that may be used to diagnose it.
Colon cancer
Colorectal cancer impacts the colon and rectum. Image courtesy: Shutterstock
Dr Praveen Bansal Published: 20 Sep 2022, 14:00 pm IST
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Cancer of the colon begins in the large intestine when the healthy cells grow out of control and form a mass called a tumor. The tumor can be benign or cancerous. Since the latter is malignant, spreads to other parts of the body while the benign one does grow but will not spread. These changes usually develop over the years and can be triggered by both genetic and environmental factors. However, at times, the changes can occur in a matter of months or few years if a person has an uncommon inherited syndrome.

What are the early warning signs of colon cancer?

Colorectal cancer usually has no symptoms in the early stages of the disease and for this reason, the condition can go undetected. When symptoms do appear, they are likely to vary in different individuals depending on the location and size of the tumor in the large intestine.

Some of the common signs and symptoms of colon cancer include change in your bowel habits, blood in your stool, abdominal discomfort, weakness or fatigue, and unexplained weight loss. While there are multiple tests for diagnosing the condition, your doctor may choose a particular diagnostic test based on the certain factors like, type of cancer, signs and symptoms, medical and family history, age and overall health, etc.

Let’s learn more about the different diagnostic tests for colorectal cancer:

1. Colonoscopy test

Colonoscopy is a test which allows a complete view of the inside of the entire rectum and colon while a patient is sedated. If a patient is found to be suffering from colorectal cancer, until the tumor is surgically removed, a complete diagnosis that accurately describes the location and spread of the cancer may not be possible.

colorectal cancer
Here are a few known tests of colorectal cancer. Image Courtesy: Shutterstock

2. Biopsy test

A biopsy is the only test to make a definite diagnosis of colorectal cancer. It involves removal of a small amount of tissue for microscopic examination. It may either be performed during a colonoscopy or may be done on any tissue removed during surgery. A CT scan or an ultrasound may sometimes be used to help perform a needle biopsy.

3. Biomarker testing

Biomarker testing, also called as molecular testing of the tumor may be recommended on a tumor sample to identify specific genes, proteins, and other factors unique to the tumor. Results of these tests may be helpful to determine your treatment options.

Also, read: Is there a link between cancer and diabetes?

4. Blood test

Colorectal cancer often results in bleeding into the large intestine or rectum. Due to this, patients with the condition may become anemic. Blood tests involve testing the number of red blood cells in the blood and this can indicate that bleeding may be occurring. Carcinoembryonic antigen (CEA) test is a form of blood test that detects the levels of a protein called carcinoembryonic antigen and high levels of this protein indicates the spread of cancer to other parts of the body. However, it is not used as a screening test for colorectal cancer, rather it is useful for patients undergoing treatment for the condition.

5. Computed tomography (CT) scan

Computed tomography (CT) scan uses X-rays to take pictures of the inside of your body from different angles. A computer then combines these pictures to show any abnormal tumors. It can be used to measure the size of the tumor as well. The scan often performed prior to surgery scan can check for the spread of cancer to the lungs, liver, and other organs.

6. Magnetic resonance imaging (MRI)

Magnetic resonance imaging (MRI) makes use of magnetic fields, to produce detailed images of the body. The imaging test can be used to measure the tumor’s size and is considered best to find where the colorectal cancer has grown.

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7. Ultrasound

Ultrasound uses sound waves to find the spread of cancer and is commonly used to find how deeply rectal cancer has grown and can be used to help plan treatment. However, it is not an accurate test to detect cancer that has spread beyond the pelvis or to nearby lymph nodes.

8. Chest x-ray

Chest x-ray can help to find out if the cancer has spread to the lungs.

colorectal cancer
Keep your fears aside for colorectal cancer test. Image courtesy: Shutterstock

9. Positron emission tomography (PET)

Positron emission tomography (PET) or PET-CT scan combines a CT scan and PET scan. PET scans are used in specific situations and are not meant for all patients suffering from colorectal cancer.

Is colon cancer easily preventable?

Some of the lifestyle changes that you can do to reduce your risk of colon cancer include maintaining a healthy weight, staying away from smoking and drinking alcohol, and making sure to exercise at least 30 minutes on most days. Besides, eat a variety of fruits, vegetables, and whole grains as they contain vitamins, minerals, fiber and antioxidants, which help the body ward off diseases and may play a role in the prevention of cancer.

Treatment for colon cancer

For some with an increased risk of colorectal cancer, it is best to discuss with your healthcare provider to determine whether preventive medications are safe for you. There are some medications that are found to reduce the risk of precancerous polyps or colon cancer and some evidence links a reduced risk of polyps and colon cancer to regular use of drugs like aspirin. However, these options are reserved for those with a high risk of colon cancer and not the ones with a low to average risk of the disease.

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About the Author

Dr Praveen Bansal, Director- Medical Oncology Asian Hospital Faridabad ...Read More

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