Aren’t there other tests that could detect colon cancer? The thought of a colonoscopy makes me nervous.
Sure there are, but not all screening techniques are equal. At a minimum, each man and woman should have an annual fecal occult blood test (FOBT), which uses a smear of stool on a specially treated card, with their primary care physician plus a flexible sigmoidoscopy (which looks at a short segment of the bowel) every three to five years or a colonoscopy every ten years. A patient might have a negative FOBT but have precancerous or cancerous growths in the colon. A sigmoidoscopy detects cancers with 45% less accuracy than a colonoscopy. A barium enema, done in the Radiology department, detects only 30-50% of cancers compared to a colonoscopy.
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Why does a colonoscopy detect more cancers than other methods?
A colonoscopy examines the entire length of the lower bowel, and provides the opportunity to remove and biopsy polyps.
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What is a polyp?
A polyp is a mass of overgrown tissue on the surface of the bowel. By age 50, one in four people have polyps. Removing a cancerous polyp before it penetrates the bowel wall is essential. Virtually all colon cancer develops from adenomatous polyps in the colon, generally referred to simply as colon polyps. A personal or family history of polyps puts one at higher risk for colon cancer. Polyps don't always become cancerous, but risk of developing cancer increases with the number and size of colon polyps seen.
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How frequently are polyps cancerous?
Approximately one percent of polyps with a diameter less than a centimeter are cancerous. If there is one polyp that size, the American Cancer Society (ACS) recommends that the doctor remove it and that a repeat colonoscopy is done three to five years later. Without any polyps, the recommended repeat date is ten years later. If there is more than one polyp or the polyp is bigger than a centimeter, there is an even higher risk for colon cancer. Up to 50% of polyps greater than two centimeters (about the diameter of a nickel) are cancerous.
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What about a family history of colon polyps…does that change anything?
When it comes to polyps and colon cancer risk, family history is important. If one or two first degree relatives (defined as parents, siblings, or children) have ever had any colon polyps, the American Cancer Society (ACS) recommends a first colonoscopy at age 40 or ten years before the age when the relative's polyp was found, whichever is earlier. So if a brother had a polyp removed when he was 45, the ACS recommends a colonoscopy when at 35 for the patient.
Here is what the American Cancer Society writes about the Familial link to colon cancer:
Familial disease
About 30% of people who develop colorectal cancer have disease that is familial. People who have a strong family history of colorectal cancer (as defined above), especially if the relatives are affected before the age of 60, are considered at increased risk of developing this disease. People with a family history of colorectal cancer need to talk with their doctor about beginning colorectal cancer testing at a younger age than age 50.
Inherited disease
About another 10% of people who develop colorectal cancer have an inherited genetic susceptibility to the disease. Approximately, 3% to 5% of colorectal cancers are associated with the inherited colorectal cancer syndrome, called hereditary non-polyposis colorectal cancer (HNPCC), or Lynch syndrome. Another 1% of colorectal cancer cases are associated with the inherited syndrome, called familial adenomatous polyposis (FAP).
Familial adenomatous polyposis (FAP) is a disease where people typically develop hundreds of polyps in their colon and rectum. Usually this occurs between the ages of 5 and 40. Cancer usually develops in 1 or more of these polyps beginning at age 20. By age 40, almost all people with this disorder will have developed cancer if preventive surgery is not done. FAP is sometimes associated with Gardner syndrome, a condition that involves benign (non-cancerous) tumors of the skin, soft connective tissue, and bones. About 1% of all colorectal cancers are due to FAP.
Hereditary nonpolyposis colon cancer (HNPCC) is another clearly defined genetic syndrome. It accounts for 3% to 5% of all colorectal cancers. This syndrome also develops when people are relatively young. These people have polyps, but they only have a few, not hundreds as in FAP. Women with this condition also have a very high risk of developing cancer of the endometrium (lining of the upper part of the uterus). Other cancers associated with HNPCC include cancer of the ovary, stomach, small bowel, pancreas, kidney, ureters (tubes that carry urine from the kidneys to the bladder), and bile duct.
Doctors have found that most families with HNPCC have certain characteristics:
- At least three relatives have colorectal cancer.
- Two successive generations are involved.
- At least one relative had their cancer when they were younger than age 50.
- At least two of the people are first-degree relatives.
These are called the Amsterdam criteria. If any of these hold true for your family, then you might want to seek genetic counseling. But even if your family history satisfies the Amsterdam criteria, it doesn’t mean you have HNPCC. Only about 60% of families who have the Amsterdam criteria have HNPCC. The other 40% do not; and although their colorectal cancer rate is higher than normal (about 2 times), it is not as high as that of people with HNPCC (about 6 times).
A second set of criteria for HNPCC, which has been recently revised, is called the Bethesda criteria. These are used to determine whether a person with colorectal cancer should have their cancer tested for genetic changes called microsatellite instability (MSI). These criteria include at least one of the following:
- The person is younger than 50 years.
- The person has or had another cancer (endometrial, stomach, pancreas, ovary, kidney or ureters, bile duct) that is associated with HNPCC.
- The person is younger than 60 years and the cancer has certain characteristics seen with MSI when viewed under the microscope.
- A first-degree relative has been diagnosed with a non-colorectal cancer often seen in HNPCC carriers (endometrial, stomach, pancreas, ovary, kidney, ureters, or bile duct) and is younger than 50 years.
- The person has two or more second-degree relatives who had an HNPCC-related tumor at any age.
MSI testing is the first step in laboratory testing to identify people with HNPCC. If a patient meets Bethesda criteria and has a tumor with MSI, more genetic testing will be needed to confirm that there is a mutation of one of the HNPCC genes. Still, the majority of people who meet the Bethesda criteria do not have HNPCC. On the other hand, about 2% of people with colorectal cancer who do not meet any of these criteria still have HNPCC when they are tested.
Doctors should also be suspicious of HNPCC if, instead of colorectal cancer, the family members have other cancers associated with this gene mutation. These are endometrial cancers, ovarian cancers, small bowel cancers, or cancer of the lining of the kidney or the ureters. Still, 1 family member younger than age 50 must have been diagnosed with colorectal cancer before a diagnosis of HNPCC is considered.
Accurate identification of families with these inherited syndromes is important. Then doctors can recommend specific measures, such as screening and other preventive measures, at an early age. Because several types of cancer can be associated with inherited colorectal cancer syndromes, all people should check their family medical history for polyps or any type of cancer. Those who develop polyps or cancer should inform other family members. People with a family history of colorectal polyps or cancer should consider genetic counseling, to review their family medical tree and determine whether genetic testing may be right for them. This will help them to make decisions about getting screened and treated at an early age.
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Besides colon polyps, is there anything else that might increase my risk of colon cancer?
You should begin screening earlier if you have a personal or family history of colorectal cancer (which can involve the colon, the rectum, or both), polyps, rectal bleeding or long-standing inflammatory bowel disease such as ulcerative colitis.
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Tell me more about Inflammatory Bowel Disease and increased risk. What is the connection?
Chronic inflammatory bowel disease (IBD), including ulcerative colitis and Crohn's disease, is a condition in which the colon is inflamed over a long period of time. If you have chronic inflammatory bowel disease, your risk of developing colorectal cancer is increased. You should start being screened by colonoscopy 8 to 12 years after you were first diagnosed with IBD and testing should be repeated frequently (every 1 to 2 years). Often the first sign that cancer may be developing is called dysplasia. Dysplasia is a term that refers to cells that are no longer normal but they are not cancer yet. Inflammatory bowel disease is different than irritable bowel syndrome (IBS), which does not carry an increased risk for colorectal cancer.
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Are men at higher risk than women for developing colon cancer?
Colorectal cancer affects an equal number of men and women. Colorectal Cancer is the second leading cause of cancer deaths in the United States. The number of new cases and the number of deaths to colorectal cancer has been decreasing as preventative screening and colon health awareness has increased.
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Why is age so important in screening for colorectal cancer?
The risk of colorectal cancer tends to increase after the age of 40. Beginning at age 50, all men and women should be screened for colorectal cancer, even if they are not experiencing problems or symptoms. Annually, approximately 130,000 new cases of colorectal cancer are diagnosed in the United States and 56,000 people die from the disease. It has been estimated that increased awareness and screening could save 30,000 lives each year.
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What are the risks for women?
After lung cancer and breast cancer, colorectal cancer is the third leading cause of cancer deaths in women in the United States.
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Does race affect colorectal cancer screening recommendations?
The American College of Gastroenterology recommends that African Americans should have colon screening for cancer at age 45, instead of 50. The recommendation is because African Americans are diagnosed with colorectal cancer at a younger age than Caucasians. African Americans who develop colorectal cancer have decreased survival, compared with Caucasians. They further recommend colonoscopy to be the preferred screening procedure for colorectal cancer for African Americans rather than flexible sigmoidoscopy because of the high overall risk as well as evidence that African American have more right-sided cancer and polyps. The right side of the colon cannot be reached with flexible sigmoidoscopy.
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How is a colonoscopy done?
Colonoscopy is almost always done on an outpatient basis. A mild sedative is usually given before the procedure and then a flexible, slender tube is inserted into the rectum to look inside the colon. The test is safe and the procedure itself typically takes less than 30 minutes. It is a camera-assisted study of the internal structures and tissues of the entire large intestine, which is also known as the colon, the rectum, and the anus. Samples of tissue (known as biopsies) can be taken at the time of the procedure.
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How does a patient prepare for a colonoscopy?
Preparation for the test includes a bowel cleansing routine, which will be prescribed by the doctor performing your colonoscopy, to clear any stool from the colon, and nothing to eat or drink after midnight on the day of the test. It is usually performed as an outpatient procedure with mild sedation and pain medicine. You will need someone who can drive you home afterwards, since you will be a little drowsy and will not be allowed to drive or operate machinery that day.
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Why is early detection so important?
There were 106,680 new cases of colon cancer in 2006 and 55,170 deaths from colon and rectal cancers combined. When colon cancer is localized to the bowel and surgical resection of the affected bowel is the primary form of treatment, the cure rate is 50%. The longer cancerous cells stay inside the bowel, the more damage they can cause.
Why is that?
The prognosis of patients with colon cancer is related to the following:
- Degree of penetration of cancer cells through the bowel wall.
- Presence or absence of lymph node involvement.
- The presence of metastasis (spread of cancer cells to other parts of the body.)
Early detection and treatment is therefore essential to a patient’s outcome.
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What are the Colon Cancer Risk Factors?
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Summary of Recommendations for Screening and Surveillance Colonoscopy in Individuals at Increased Risk for Colorectal Cancer
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Can you explain more about each type of screening test for colorectal cancer?
Exams and Tests Explained:
- For a digital rectal exam, the doctor gently inserts a gloved, lubricated finger into the rectum and feels for abnormal areas. Fifteen percent of colorectal cancers can be detected by digital rectal examination.
- The stool test for blood (FOBT) checks for hidden or occult blood in the stool. Sometimes colorectal cancers can cause bleeding that cannot be seen. For this test, a small amount of stool is placed on a plastic slide or on special paper. The stool may be tested in the doctor's office or sent to a lab.
- A sigmoidoscopy exam allows the doctor to visualize up to 25 inches of the lower bowel. For this exam, the doctor gently inserts a small, flexible, lighted tube into the rectum and lower colon. Approximately 72% of all colorectal cancers occur in this area.
- A colonoscopy is an examination of the rectum and entire colon using a lighted instrument called a colonoscope. Colonoscopy can find precancerous or cancerous growths throughout the colon, including the upper part of the colon, where they would be missed by sigmoidoscopy. However, it is not known whether this benefit outweighs the risks of colonoscopy, which include possible bleeding, and puncturing of the lining of the colon. More research is needed to address these issues.
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Is there anything that should I be looking for to report to my doctor that might indicate a need for earlier screening or screening out of the expected interval of every ten years?
Symptoms to Report to Your Doctor:
- A change in usual bowel habits (constipation, diarrhea, or both)
- Stools that are narrower than usual
- Blood in or on the stool
- General stomach discomfort, such as bloating, fullness and/or cramps
- Frequent gas pains
- A feeling that the bowel does not empty completely
- Weight loss with no known reason
- Constant tiredness
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How can I contact the GI Center to schedule an appointment?
After discussing a screening colonoscopy with your primary care physician and having obtained a referral for the procedure, call 773.564.5199 to schedule your test.
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I live alone and don’t have anyone to drive me to the test. What can I do?
Weiss offers a Courtesy Van to help with your transporation needs.
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References:
- American Society of Gastrointestinal Endoscopy (ASGE) Colon Screening Facts, 2006
- Buetow, P. and Buck, J. "Colorectal Adenocarcinoma." RadioGraphics 15.1 (Jan. 1995). 28 Aug. 2006
- “Colonoscopy in the Screening and Surveillance of Individuals at Increased Risk for Colorectal Cancer” A SAGES Co-Endorsed ASGE Guideline, 2006.
- What Are The Risks For Colon and Rectum Cancer?
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