Contents:
- Medical Video: Colorectal Cancer Screening
- What tests might a doctor recommend to ensure a diagnosis of colon cancer?
- Biopsy
- Lab sample test
Medical Video: Colorectal Cancer Screening
The diagnosis of colon cancer plays an important role in determining genetic risk, detecting cancer at an early stage, and determining the characteristics and possible spread of the disease. Cancer screening can help doctors make your treatment plan and monitor the effectiveness of cancer. It is important to understand the various screening and diagnostic tests used in the detection and treatment of colon cancer. Consult with your doctor about the complaints you feel.
What tests might a doctor recommend to ensure a diagnosis of colon cancer?
Biopsy
If the doctor suspects the potential for colon cancer during the initial examination, the intestinal tissue sample will be biopsied with a colonoscopy. In a biopsy, the doctor takes a small piece of intestinal tissue with a special instrument that is passed through the colonoscope. Usually, a slight bleeding will occur after this procedure, but it will stop after a while. Parts of the large intestine may need to be removed surgically to make a diagnosis, but this is rare.
Lab sample test
Samples obtained from biopsies (via a colonoscopy or surgery) are sent to a laboratory where the pathologist checks them with a microscope. Pathologists are doctors who are trained to determine the diagnosis of colon cancer and other diseases through tissue samples. Other tests can be recommended if colon cancer is found, but the only way to be sure is to examine the sample with a microscope.
The following are two types of laboratory tests commonly used to confirm the diagnosis of colon cancer:
Gene test
Other lab tests can also be done on biopsy specimens to help classify cancer better. Doctors can check changes in specific genes in cancer cells that can affect the best treatment methods. For example, doctors now usually test cells for changes in the KRAS gene. This gene mutates in about 4 out of 10 colorectal cancers. Some doctors can also test changes in the BRAF gene. Cancer patients with mutations in one of these genes do not benefit from treatment with certain anti-cancer drugs such as cetuximab (Erbitux®) and the general committee (Vectibix®).
MSI Testing
Sometimes the tumor tissue will be tested to see if a change is called microsatellite instability (MSI). This change is found in most colorectal cancers caused by hereditary non-polyposis colon cancer (HNPCC) and can also affect some cancers in patients who do not have HNPCC. There are 2 reasons for testing colorectal cancer for MSI. The first reason is to identify patients who must be tested for HNPCC. A diagnosis of HNPCC can help plan further screening in patients (for example women with HNPCC may need to be screened for uterine cancer). In addition, if patients are known to have HNPCC, their relatives can also have it, and may also want to be tested. If they really have HNPCC, their risk of getting cancer will increase and need further screening. The second reason is to know that early stage colorectal cancer has MSI can change the way it is treated.
Some doctors recommend MSI testing only if the patient meets certain criteria. Other doctors tested all colon cancer for MSI, and the rest still determined based on the age of the patient or the stage of the cancer. There are several ways to test MSI. One way is to start a DNA test for MSI. The second way is to do a test immunohistochemistry first to see if certain proteins associated with MSI are not found in cancer cells. If this test looks suspicious, then a DNA test for MSI will be carried out. Not all patients have cancer cells that show MSI has HNPCC. To test HNPCC, blood is taken to examine changes in the genes causing HNPCC in the DNA of blood cells.
Hello Health Group does not provide medical advice, diagnosis or treatment.
