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5 Tests to Identify Colon Cancer?


Colon cancer is one of the most common cancers of the digestive tract. The cases of colon cancer are on the rise in India, especially in young patients. So it’s become very important to diagnose and treat this cancer at the earliest stage.

In this blog, we will look at some of the most common tests a doctor might recommend if you have colon cancer. So let’s get started.


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What is Colon Cancer?

The colon or large intestine is the last part of our digestive tractṣ system. It’s 5 feet long and collects the waste that remains after everything useful is digested and absorbed by the stomach and small intestine.

Colon cancer is cancer that appears in the colon. It starts from the colon’s inner lining, also known as mucosa. It spreads gradually and reaches other layers after a certain period.

In the later stages, colon cancer can also spread to other organs like the lungs and liver. Sometimes, it spreads to the lymph nodes too. The most common symptoms of colon cancer involve:

  •   Blood in the stool
  •   Change in bowel habit
  •   Unexplained weight loss
  •   Irregular excretion cycle

If you are experiencing these symptoms and you are above 50 years or you are younger, but these symptoms are not going away even after two to three weeks, you need to consult a doctor.

A doctor will suggest some tests to help diagnose whether you have colon cancer. These tests can also help determine the cancer stage if you are diagnosed with cancer.

Why are Tests Necessary?

The tests for colon cancer are necessary to:

  •  Confirm the diagnosis
  • To grade the disease
  • To Stage the disease
  • To determine the further plan of action and treatment plan

So we need tests that can help with all the above four causes.

Now, let’s look at the 5 most common tests doctors recommend to diagnose colon cancer.

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5 tests to Diagnose the colon cancer

1. Colonoscopy:

Under this test, we use a long flexible tube with the camera at its tip. We insert this tube via the rectum to examine the whole intestine.

We thoroughly examine each and every part of the intestine where there is a possibility of polyp or fibroid. This is an OPD-based test, i.e. it can be completed within a single day.

We give either local anaesthesia or general anaesthesia, depending on the patient’s condition. This test is not painful, but some patients might experience a little bit of temporary discomfort.

But, Colonoscopy is one of the most preferred tests to diagnose colon cancer. The reason is it gives us a clear view of each and every part of the colon where there is a possibility of cancer.

Moreover, it allows us to take the biopsy for further lab testing. Further testing of the sample at the pathological lab can help us determine whether the patient has cancer.

Sometimes pathological tests are not enough. In such cases, we perform an Immunohistochemistry test to identify whether the patient has cancer or not.

There is another version of Colonoscopy called sigmoid Colonoscopy. In this test, we take a look at a particular section of the colon, known as the sigmoid colon.

There are certain additional benefits to Colonoscopy too. E.g., if the cancer tumour is large and obstructs the movement of the stool in the intestine, we can widen that particular section with a colonoscopy.

This can give a patient some temporary relief. We can also place a stent using a colonoscopy, which could be a temporary solution while we devise the complete treatment plan.

2. CT Scan -:

CT scan is one of the most common tests conducted for various health conditions. If the doctor suspects you have colon cancer, he/she might recommend a CT scan of the abdomen or pelvis.

At Oasis Clinic, we recommend a CT scan with contrast that helps determine the exact location of cancer.

A CT scan can help us determine the approximate stage of cancer. It can also indicate whether the cancer is confined to the colon or has spread to other organs or lymph nodes too.

If it’s spread in the liver, the CT scan can confirm this too. So we advise the CT to think of the abdomen and chest together for complete screening.

 3. MRI scan: Usually, MRI cancer plays a limited role in colon cancer. It’s more useful in the case of rectal cancer. MRI can help determine the stage and spread of rectal cancer better than a CT scan. 

4.  PET Scan

Positron Emission Tomography or PET scan is a complete body screening and check-up test. During this test, we inject a medicine called FDG into the patient’s body and then scan the patient’s whole body.

With the help of FDG, a PET scan can identify even a small tumour of 1 to 1.5 cm, which is a great advantage. Such detailed testing is not possible with the CT scan. 

It’s important to note that a PET scan is not a necessary investigation. But if your doctor suspects that cancer has spread to some other organs, along with the colon, he/she might recommend this test.

Sometimes, the PET scan is done before the surgery and after the surgery to ensure no cancer tumours are left in the body.

5. Tumour Marker:

The Tumour market is another way to diagnose cancer. A Tumour marker is a chemical that’s released from the tumour into the bloodstream of the patient. Measuring its levels in the blood can help diagnose colon cancer.

The tumour marker levels can also help us determine the approximate aggressiveness of and the spread of the tumour.

The specific tumour marker of colon cancer is called Carcinoembryonic antigen (CEA). It’s very important to measure the CEA level before performing any surgery for the treatment of colon Cancer.

It gives us a baseline idea about the potential spread of the tumour. If its levels are too high, it can also give us an idea about the prognosis (survival chances).

Similarly, if the CEA levels decrease after the treatment, it can indicate the success of the treatment.

Moreover, we perform tumour marker tests during the follow-ups of the patients whom we have treated. If the marker levels rise, it can be an early indication that the tumour has Returned.

This helps us treat the patient at an early stage, improving the chances of successful treatment.

 Apart from these 5 tests, there are other tests too that can help determine your fitness levels. One of these tests includes the CBC test.

In some cases, excessive bleeding might reduce the haemoglobin in colon cancer patients. In such patients, surgery and chemotherapy are not possible.

So, tests like CBC can be very helpful in such conditions. Other tests like X-ray, 2d Echo test, ECG test and Liver & Kidney function test can help us in surgical planning.

Wrapping up

The severity and the treatment plans of colon cancer are determined based on these tests. So these tests play a pivotal role in colon cancer treatment.

We hope you find the information in this blog very useful and helpful. In case if you need any further information regarding the tests for colon cancer or anything else related to colon cancer, feel free to reach out. Our experts will help you out. 

Dr. Aditya Kulkarni

MS, DNB, FRCS, MCh (Surgical Gastroenterology & GI Oncology)

Dr. Aditya Kulkarni is a Consultant of Laparoscopic and Robotic Gastrointestinal, Hepato-biliary-pancreatic, and Cancer Surgeon at the Renowned Oasis Surgery Clinic Pune.

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