Colorectal Cancer: Diagnosis
How is colorectal cancer diagnosed?
Your doctor might suspect you have colorectal cancer based on the results of a screening test to look for the cancer early. Or you might have symptoms that could be caused by colorectal cancer. You will need certain exams and tests to be sure. The process starts with your healthcare provider asking you questions. He or she will ask you about your
Family history of disease
Your healthcare provider will also give you a physical exam.
What is a biopsy?
A biopsy is the removal of cells or tissue to be examined under a microscope. This exam can show if the tissue is cancer. For colorectal cancer, a biopsy is the only way to be sure of the diagnosis. The most common type of biopsy is an endoscopic biopsy. This is usually done during a colonoscopy. Other types of biopsies include a needle biopsy and a surgical biopsy. But these are not often used to diagnose colorectal cancer. Needle biopsies are sometimes used in other parts of the body to see if the cancer has spread. Surgical biopsies are used to take samples of large tumors. They are also used for tumors in hard-to-reach places.
Once your healthcare provider removes the tissue, he or she sends it to a lab. There a doctor called a pathologist looks at the tissue under a microscope to check for cancer cells. It usually takes several days for the results of your biopsy to come back. A biopsy is the only sure way to tell if you have cancer. And it is the only way to tell what kind of cancer it is.
Below are the 3 types of biopsies a healthcare provider may do:
This is most common biopsy to diagnose colorectal cancer. It is done during a colonoscopy or a sigmoidoscopy. These are screening and diagnostic tests that use an endoscope. This is a tube with a small video camera on the end. There are types of endoscopes for different parts of the body. For a colonoscopy, the healthcare provider uses a colonoscope. For a sigmoidoscopy, he or she uses a sigmoidoscope. It is shorter and can only reach about 1/3 of the colon. If the healthcare provider finds a polyp or growth in the colon or rectum during 1 of these tests, he or she most likely will remove it. This is done using small tools passed down the endoscope. After cutting it from your colon wall, the healthcare provider will take it out through the tube. This is called a polypectomy. Your healthcare provider then sends the polyp to the lab to be checked for cancer. He or she will also take samples of any other growths to send to the lab. The lab will then be able to see if any of the growths are cancer.
There are 2 types of needle biopsies. One is a fine needle biopsy. The healthcare provider uses a very thin (fine) needle and syringe to remove liquid and a very small sample of tissue. The other is a core needle biopsy. The needle for this procedure is slightly larger. This biopsy is sometimes done to take tissue from a tumor found in some other part of your body, such as the liver. This test can help show if the cancer has spread. For a needle biopsy, the healthcare provider inserts a needle into the tumor and takes a sample of tissue. For tumors the doctor can feel, the biopsy can be done in the healthcare provider's office using a local anesthetic. For tumors that can't be felt, the healthcare provider may use a CT scan to help guide the needle. CT scans are detailed X-rays. Or your healthcare provider may use an ultrasound to help him or her guide the needle. These types of biopsies are done in a procedure room. A needle biopsy usually takes only a few minutes. You may receive sedation if needed to ease the discomfort. You don’t need to stay in the hospital overnight.
Most biopsies can be done with 1 of the above methods. But if the polyp or mass the healthcare provider wants to examine is large or in a hard-to-reach spot, you may need to have surgery. You'll be given general anesthesia so that you fall asleep and don't feel anything. You may also have to stay overnight in the hospital. It may take several days before you can go back to your normal routine.
Most polyps are benign. That means they are not cancer. The biopsy will show exam will reveal if the polyps are abnormal cell growth (dysplasia) or cancer (carcinoma). If you have a dysplastic polyp, you are at higher risk for growing more polyps and cancer.
Getting your test results
When your healthcare provider has the results of your biopsy, he or she will contact you with the results. Your provider will talk with you about other tests you may need if colorectal cancer is found. Make sure you understand the results and what follow-up you need.
March 16, 2019
Clinical presentation, diagnosis, and staging of colorectal cancer, UpToDate
Alteri, Rick MD,Levy, Adam S, MD