Diagnosis and Prognosis of Colorectal Cancer
The diagnosis and prognosis of colorectal cancer includes the following:
Review of Medical History and Physical Exam
Your doctor will ask about your symptoms and medical history. He or she will also ask about specific risk factors for colorectal cancer, for example, if anyone in your family has had colorectal cancer or if you have (or have had) other conditions associated with colorectal cancer. These include:
- Ulcerative colitis
- Crohn’s disease
- Gardner’s syndrome
- Cancer of the ovaries, uterus, or breast
- Previous colorectal cancer
Your doctor will also ask about your lifestyle, as some behaviors may increase the risk of colorectal cancer. These behaviors include smoking, eating a high-fat diet, drinking alcohol regularly, and not exercise.
Your doctor will do a thorough physical exam. This will include a digital rectal exam. This exam is done to check for abnormal lumps or growths in the rectal area. To do this test, your doctor inserts a lubricated gloved, finger into the rectum, and gently probes for any growths. The exam takes only a few minutes and is performed in the doctor’s office.
If, based on your medical history, symptoms, and exam, your doctor suspects you may have colon cancer, some of the following tests will be done.
X-ray of the large intestine – an x-ray will provide a picture to help identify the presence of polyps.
Fecal occult blood test – this test identifies the presence of occult (hidden) blood in the stool, which would signify bleeding, possibly caused by the presence of a tumor.
For this test, which can be done by your doctor during your exam or by you at home, a small sample of stool is placed on a special card and tested by a lab for hidden blood.
Sigmoidoscopy – this test enables the doctor to view the inside of the lower colon and rectum for polyps, tumors, or abnormal growths. This test can be done in your doctor’s office.
A day or two prior to the test, you will need to completely eliminate all waste from your lower intestine. This is usually done by drinking a medication that acts as a laxative, or by having an enema (a substance that is squirted into the rectum and causes bowel movements). On the day of the test, you will be given a sedative to ease discomfort.
The doctor will insert a sigmoidoscope (a thin, lighted flexible tube with a tiny camera attached) into the rectum to view the inside of the lower colon and rectum and look for polyps, tumors, or abnormal growths. The doctor will give you a preliminary report of the results when the sigmoidoscopy is completed.
Colonoscopy – this test enables the doctor to view the inside of the entire colon and rectum for polyps, tumors, or abnormal growths.
A day or two prior to the test, you will need to completely eliminate all waste from your lower intestine. This is usually done by drinking a medication that acts as a laxative, or by having an enema (a substance that is squirted into the rectum and causes bowel movements). On the day of the test, you will be given a sedative to ease discomfort. The doctor will insert a colonoscope (a thin, lighted flexible tube with a tiny camera attached) into the rectum and bowel. The camera transmits the image of your colon onto a video screen, which allows your doctor to view and examine any abnormalities inside the colon.
If a polyp or abnormal tissue is discovered during this exam, it may be removed and reviewed for further testing. If tissue is removed, a small amount of bleeding may occur during the first two days after the procedure. This procedure takes less than one hour and is usually done in a hospital or doctor’s office.
The doctor will usually give you a preliminary report after the medication wears off and you are more alert. The results from a biopsy can take as long as one to two weeks to be completed, so schedule a follow-up appointment with your doctor.
Barium Enema – a barium enema is a rectal injection of barium given to coat the lining of the colon and rectum. It is done before x-rays are taken in order to create better x-ray images. X-rays are taken of the colon and/or rectum to look for polyps, abnormal growths, or a thickening of the lining of the colon or rectum.
For this procedure, a well-lubricated enema tube is gently inserted into the rectum. Barium is injected through this tube into the colon and rectum. A small balloon at the end of the tube is inflated to keep the barium inside. X-rays are taken. After x-rays are taken, the enema tube is removed, and you are shown to the bathroom to expel the barium. The procedure will last one to two hours.
Polypectomy – during a sigmoidoscopy or colonoscopy, if your doctor sees a polyp, he or she may remove a sample (biopsy) for testing.
Biopsy – removal of a tissue sample from a polyp for examination by a pathologist.
If the presence of cancer is confirmed by a biopsy, a laboratory pathologist will evaluate the cancerous sample to determine how far it has spread in the body.
Staging is the process by which physicians determine the prognosis of a cancer that has already been diagnosed. Staging is essential for making treatment decisions (e.g., surgery vs. chemotherapy). Several features of the cancer are used to arrive at a staging classification, the most common being the size of the original tumor, extent of local invasion, and spread to distant sites (metastasis). Low staging classifications (0 – 1) imply a favorable prognosis, whereas high staging classifications (4 – 5) imply an unfavorable prognosis.
Staging is an attempt to determine whether the cancer has spread from the inner lining of the colon, and, if it has, what body parts are affected.
If cancer is found, the prognosis and treatment depend on the location, size, and stage of the cancer and your general health.
Additional tests to determine the cancer’s stage may include:
- Urine and blood tests
- X-rays of various parts of the body, including lungs, bladder, kidneys, lymph nodes
- Barium enema to check the colon and rectum
- CT scan – a type of x-ray that uses a computer to produce cross-sectional images of the inside of the body
- Ultrasound – the use of sound waves and the characteristic patterns they make bouncing off of various structures in the body to identify tumors and other conditions
- MRI scan – a test that uses magnetic waves to produce images of the inside of the body; using a large magnet, radio waves, and a computer, an MRI produces two-dimensional and three-dimensional pictures
Stages of Colorectal Cancer
If colorectal cancer is diagnosed, the following staging classification is used to identify how and where the cancer has spread:
- Stage 0 (also called “carcinoma in situ”): in this stage, abnormal cells are found only in the innermost lining of the colon.
- Stage I (also called Dukes’ A colon cancer): cancer has spread beyond the innermost lining of the colon to the second and third layers, and involves the inside wall of the colon. However, it has not spread outside the colon wall.
- Stage II (also called Dukes’ B colon cancer): cancer has spread beyond the muscular walls of the colon and has spread as far as the fat or thin skin that surrounds the colon and rectum. It has not yet gone to the lymph nodes. Lymph nodes are bean-shaped structures found throughout the body that help filter lymph, and fight infection and disease.
- Stage III (also called Dukes’ C colon cancer): cancer has spread to nearby lymph nodes, but not to other parts of the body.
- Stage IV (also called Dukes’ D colon cancer): cancer has spread to other parts of the body, such as the liver and lungs.
- Recurrent: this term describes cancer that has returned after treatment.
Prognosis is a forecast of the probable course and/or outcome of a disease or condition. Prognosis is most often expressed as the percentage of patients who are expected to survive over five or ten years. Cancer prognosis is a notoriously inexact process. This is because the predictions are based on the experience of large groups of patients suffering from cancers at various stages. Using this information to predict the future of an individual patient is always imperfect and often flawed, but it is the only method available. Prognoses provided in this monograph and elsewhere should always be interpreted with this limitation in mind. They may or may not reflect your unique situation.
Survival from colorectal cancer is a function of the stage of the tumor, and the patient’s overall health or performance status. Five-year cause specific survival (or survival purely related to the tumor and not another disease the patient may have) is as follows:
- Stage I: 90%
- Stage II: 80%
- Stage III: 65%
- Stage IV: 10%
Last reviewed February 2003 by
Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.
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