Early Detection of Colorectal Cancer & Colorectal Polyps

Colorectal cancer is the second most common cause of death from cancer in the United States. Early diagnosis of this disease greatly increases the chances for a cure or prolonged survival. The 5 year survival for patients with early colorectal cancer is 90%. Once the disease has spread to distant sites the 5 year survival rate is only 8 %. The American College of Gastroenterology and the American Cancer Society recommend screening by colonoscopy starting at age 50 in an average risk person in order to detect colon polyps or colon cancer at an early stage. Up to 80% of colon cancer deaths are preventable by current screening methods. In order to make recommendations for individual patients, we must first define the patient’s risk for colorectal cancer.

Patients are placed in two categories: increased risk, or no increased risk.
Screening tests are directed toward detection of a common disease in patients who have no symptoms of that disease. Screening colonoscopy is recommended for patients who are at no increased risk, beginning at age 50, then at 10 year intervals. For patients at increased risk, more frequent examinations are recommended.

Surveillance tests are performed to monitor patients who have been treated for a disease to detect recurrence. Surveillance is recommended for patients previously diagnosed with colorectal cancer or polyps. Generally, this is done with full colonoscopy at 3-5 year intervals as these patients are at increased risk for recurrent polyps and colorectal cancer.

Diagnostic tests are done to evaluate symptoms which might indicate the presence of colorectal cancer, such as rectal bleeding, change in bowel habits, or anemia. Patients who have symptoms are not undergoing screening. Colonoscopy is generally recommended as part of the patient’s evaluation for these symptoms or findings.

What are the risk factors for developing colon cancer?

Colon cancer is uncommon before age 50 but the incidence rises rapidly up to age 80 and then levels off. Persons 50 years and older who have no other risk factors for developing colorectal cancer are defined as average risk. About 85% of patients with colorectal cancer have no family history or any other identifiable risk factor. Even if you are at average, or no increased risk, you should still undergo screening for colorectal cancer.

Family History
About 25% of patients with colorectal cancer have a first degree relative who also has colorectal cancer. A history of colorectal cancer in a first degree relative doubles one’s risk for developing colorectal cancer. This risk is even higher in relatives of patients is diagnosed with colorectal cancer before age 60.
The more family members affected and the younger the patient at diagnosis the greater the risk to other family members. If you have a first degree relative diagnosed below age 70 with colorectal cancer, you are at increased risk and should undergo screening colonoscopy beginning at age 40 and at 5-10 year intervals thereafter.

Prior History of Colorectal Cancer or Colorectal Polyps
If you have been diagnosed with colorectal cancer or polyps in the past, you are clearly at increased risk for recurrent polyps and cancer. You should undergo surveillance colonoscopy at 3-5 year intervals.

Inherited Syndromes
Some patients develop colon polyps and cancer at a very early age as a result of a genetic abnormality that can be passed on to other family members. This abnormality accelerates the process by which polyps and cancer form. The highest risk is in families with colorectal cancer syndromes such as Familial Adenomatous Polyposis (FAP), Gardner’s Syndrome, and Hereditary Non-Polyposis Colorectal Cancer (HNPCC). These families require genetic counseling and screening starting at an early age. These syndromes together make up only
1- 2% of all colon cancer cases in the United States.

Ulcerative Colitis
Patients with ulcerative colitis are at increased risk for colorectal cancer. This risk increases with the duration of the disease. If the entire colon is involved, the patient should begin screening with colonoscopy about eight years after the initial diagnosis. If the disease only involves the lower portion of the left colon, screening should begin at 15 years. Colonoscopy and biopsy is done to detect dysplasia, a precancerous change.

How Does Cancer Develop?
We now understand that colon cancer develops as a multi-step process of mutation occurring in cells in the lining of the colon. Mutation may cause an increase in the rate of multiplication of a group of cells, resulting in the formation of a polyp. One of these cells then undergoes further mutation which changes it into a cancer cell which then multiplies and grows into a cancer. Research is being conducted to develop blood tests to identify patients with a genetic defect which makes them more susceptible to developing colon cancer. Tests are also being developed to detect this abnormal genetic material in the stool.

Can Colon Cancer be Prevented?

A high fiber diet, while of theoretical benefit, has not been shown to reduce the risk of colorectal cancer. Regular use of aspirin or NSAIDs (nonsteroidal anti-inflammatory drugs) such as ibuprofen, sulindac, and others, does reduce the risk of recurrent polyps. Unfortunately, these drugs also increase the risk of bleeding ulcers. This potential complication eliminates any survival advantage, so these drugs are not generally recommended for this purpose.

Colon Polyps

Colon polyps are benign, non-cancerous growths which frequently occur in the colon. Polyps gradually enlarge, and some will develop areas of cancer, which can grow and spread. Almost all colon cancers arise in polyps. If polyps are identified and removed, this sequence of events is interrupted, and the development of colon cancer can be prevented. Not all polyps are precancerous. The ones we are most concerned about are called adenomas, or adenomatous polyps. Other terms for these are villous adenomas, tubular adenomas, tubulovillous adenomas, or villoglandular polyps. Patients with these types of polyps require careful follow up to make sure all the polyps have been completely removed, and periodic repeat exams to look for recurrent polyps. The larger the polyps, and the more polyps that are found, the higher the risk of developing colon cancer. These polyps are a definite risk factor for the development of colon cancer, and patients should be carefully monitored for the rest of their lives. Removal of colon polyps has been shown to decrease the risk of death from colorectal cancer.

Screening Tests

Rectal Examination
Patients over the age of 50 should have a digital rectal examination as part of an annual physical examination. This is to detect small growths in the rectum and to check for prostate cancer in men. A blood test (PSA) may also be helpful for early detection of prostate cancer.

Hemoccult Test
A Hemoccult test should be done yearly to detect traces of blood in the stool. This is a simple chemical test to detect small quantities of blood in the stool which may not be visible to the naked eye. About a third of people with a positive test will have polyps. Only a small percentage of people with a positive test will have colon cancer. Most people with a positive test do not have colon cancer, but the risk is high enough to warrant careful testing to diagnose colon cancer if it is present. A positive test may indicate other problems in the digestive system. If your test is positive, you should see your doctor for a complete physical examination, including a rectal exam and colonoscopy. Colonoscopy is the most accurate and effective way to detect and treat colon polyps and detect colon cancer.
A negative Hemoccult test does not eliminate the possibility of colon cancer. Bleeding from these growths is intermittent and up to fifty percent of patients with colon cancer may have a negative test. For this reason, if your test is positive, a repeat test which is negative is no reassurance at all.
Please carefully follow the instructions enclosed with the Hemoccult Kit. The diet is particularly important. Various substances, especially red meat, and aspirin may interfere with the test and cause a positive result, even if no blood is present. This could lead to tests which might otherwise be unnecessary. Vitamin C can sometimes cause a false negative test.

Colonoscopy is the best screening test to examine the entire colon for polyps, cancer and other abnormalities. A colonoscope is a flexible lighted tube, which is inserted through the rectum and advanced to the end of the colon. The procedure is done under sedation to assure patient comfort. It allows the doctor to visualize the lining of the entire colon and to deal with any abnormalities at the time of the procedure. Polyps can be removed and other lesions biopsied or cauterized.
Like every other test available, colonoscopy is not perfect and there is a small risk that a colon cancer can be missed with this examination. If you have persistent rectal bleeding or other symptoms, then other testing or even repeat colonoscopy might be needed.

Barium enema is a less accurate test which also examines the entire colon. Any abnormalities found would require colonoscopy.

Flexible Sigmoidoscopy is a limited examination of the lower part of the colon. This procedure is done in the office, usually without sedation. It is recommended as a general screening examination to detect colon polyps or tumors in patients who have no symptoms of disease. We no longer recommend or offer flexible sigmoidoscopy as we consider it to be inadequate as a screening procedure.

Virtual Colonoscopy is a new test in which the patient undergoes a high speed CT scan. The computer reassembles the images to create a view of the colon that looks like what is seen at colonoscopy. Preparation still requires a laxative preparation, and the colon is filled with air to create the images. The bowel prep and air can be uncomfortable. If abnormalities are found, conventional colonoscopy may still be required. Virtual colonoscopy may not be covered by your insurance plan. The procedure is being refined, but has been shown to miss up to 25% of larger polyps and about half of smaller polyps that are detected by standard colonoscopy. Its role in colorectal cancer screening and diagnosis has not been clearly defined.

Screening Guidelines

The American College of Gastroenterology and the American Cancer Society “Colorectal Cancer Screening Guidelines” recommend that average risk persons should begin screening with colonoscopy at age 50. If this test is negative, follow up evaluation is recommended at 10 year intervals. If adenomatous polyps or other abnormalities are found your physician will advise you as to when you should undergo follow up testing. Current guidelines suggest colonoscopy at 3-5 year intervals. Interim testing with Hemoccult or flexible sigmoidoscopy is not necessary and should not be done unless the patient develops new symptoms.

Patients at increased risk, especially those with a strong family history of colorectal cancer diagnosed before age 60 should consult their physician about the most appropriate timing of their first colonoscopy. Current recommendations call for screening to begin at age 40.

Screening colonoscopy is a covered benefit under Medicare and most private insurance. Unfortunately, some insurance carriers will not pay for the examination unless the patient has symptoms or risk factors as noted above, or if polyps or other abnormalities are found at the time of the procedure. If you need or wish to undergo screening colonoscopy, and have no symptoms or risk factors, please discuss this with your physician in our office. We offer an affordable package price for this service.

We welcome your questions regarding colorectal cancer, and will be happy to discuss any symptoms or concerns. We want you to have a clear understanding of your personal level of risk and which screening tests are appropriate for you.