Diagnosis Of Colon Cancer

Doctors use different tests to diagnose cancer and some of these tests may include imaging tests and blood tests. These kinds of tests are also done to find out if the cancer has spread from where it had started. For diagnosing a type of cancer there are various factors that are looked into like, the suspected cancer, the patients signs and symptoms, the patient’s health and medical condition, medical and family history and lastly, results from previous medical tests.

Visual representation of colon cancer under a microscope

In addition to a physical exam, the following tests may be done to diagnose colon cancer.


A colonoscopy is done when a patient is sedated. It allows the doctor to look into the patients colon and also to take a sample of tissue for the confirmation of cancer. If colon cancer is found, an accurate diagnosis with the location is given by the doctor.

Molecular testing of the tumor

Laboratory tests are run on the tumor sample to check for specific genes, proteins and any other factor that might be unique to the tumor. If the person has metastatic colon cancer, a sample of the tissue from the area that it has spread too might be taken for testing. This will decide if treatment options include targeted therapy.


A biopsy is the removal of a small amount of tissue that is then examined under a microscope. A biopsy can also be seen as a definite diagnosis to see if colon cancer is present. In a biopsy, a pathologist will analyze the sample which includes evaluating cells, organs, and tissues to make a diagnosis. A biopsy can be done during a surgery or colonoscopy. A CT scan or ultrasound is used to perform a needle biopsy.

Blood tests

A blood test to check for the complete blood count of a person is done to check for anemia. If a person has anemia, which is low red blood cell count, it means the tumor has been bleeding for a long time. A blood test may also be done to check for liver function as colon cancer can spread to the liver as well.

Computed Tomography (CT) scan

A CT scan can be used to check if colon cancer has spread to the liver. In a CT scan, X-rays are used to make detailed cross sectional images of organs.


Sometimes pet-ct scan is needed to look for any distant spread from the colon cancer.Radionuclide material is used in this scan.


It is blood investigation helps in detecting and monitoring for recurrence in colon cancer. It is tumor marker. However, not all colonic cancer patients may not have raised serum cea values. In smokers also it is slightly elevated compared to non smokers.

Gene tests

Gene tests are often conducted to check to check for specific gene changes in cancer cells. This test is usually done to check how treatment might affect these cells in cases where the cancer has spread. Colon cancer cells are typically tested to check for high levels of gene changes called microsatellite instability (MSI). Testing is also done to check if the cancer cells show changes in any of the mismatch repair genes (MLH1, MSH2, MSH6 and PMS2)

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