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. If your healthcare provider thinks you might have colorectal cancer, you will need certain exams and tests to be sure. Diagnosing colorectal cancer starts with your healthcare provider asking you questions. He or she will ask you about your health history, your symptoms, risk factors, and 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 whether the tissue is cancerous. For colorectal cancer, a biopsy is needed to be sure of the diagnosis. The most common type of biopsy is an endoscopic biopsy, which is usually done during a colonoscopy. Other types of biopsies that your healthcare provider may use 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 the only way to tell what kind of cancer it is.
Here are descriptions of the three types of biopsies your health care provider may do:
The most common biopsy done to diagnose colorectal cancer is done during a colonoscopy or a sigmoidoscopy. These are screening and diagnostic tests that use an endoscope. An endoscope is a tube with a small video camera on the end used to look inside your rectum and colon. There are specific types of endoscopes used depending on what part of your body the healthcare provider is looking at. For a colonoscopy, the healthcare provider uses a colonoscope. For a sigmoidoscopy, a sigmoidoscope is used. It is shorter and can only reach about one-third of the colon. If the healthcare provider finds a polyp or growth in the colon or rectum during one of these tests, he or she most likely will remove it using instruments passed down the endoscope. After cutting it from your colon wall, the healthcare provider will take it out through the tube being used to see inside you. The removal is called a polypectomy. Your healthcare provider then sends the polyp to the lab to be checked for cancer. If the healthcare provider sees a mass or some other type of unusual tissue, he or she will remove a portion of it through the tube and send it to the lab. The lab will then be able to determine whether it is cancer.
There are two types of needle biopsies. One is a fine needle biopsy. For it, the health care provider uses a 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. The health care provider takes out a small sample of tissue about one-sixteenth of an inch in diameter. These biopsies are sometimes done to examine tissue from a tumor or a mass the healthcare provider has found in some other part of your body such as the liver. They can help the healthcare provider know whether the cancer has spread. To perform a needle biopsy, the healthcare provider inserts a needle into the tumor and withdraws a sample of tissue. The biopsy can be done in the healthcare provider's office using a local anesthetic for tumors the doctor can feel. For tumors that can't be felt, the healthcare provider may use a CT scan to help guide the placing of the needle. CT scans are very accurate X-rays that take detailed pictures of the inside of your body. Sometimes healthcare providers use an ultrasound image to help guide the insertion of the needle. These types of biopsies are done in a special operating room. A needle biopsy usually takes only a few minutes. It doesn't require you to stay in the hospital overnight.
Most biopsies can be performed with one of the above techniques. However, if the polyp or the mass the health care 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 will also probably have to stay overnight in the hospital. It may take several days before you can go back to your normal routine. Sometimes you need a formal surgical procedure even for a biopsy.
Most polyps are benign. That means they are not cancerous. Microscopic exam will reveal the nature of the polyps and whether dysplasia, which is abnormal cell growth, or carcinoma, which is cancer, is present. If you do not have cancer but do have a dysplastic polyp, you are at higher risk for developing more polyps or even 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.