Colorectal Cancer, Part 1: Risk Factors and Screening
"Colorectal cancer is one cancer where regular screening clearly has benefits. Screening saves lives."--- James S. Marks, MD, Director of the CDC's National Center for Chronic Disease Prevention and Health Promotion
You might not want to talk about it. You probably don’t even want to think about it. But colorectal cancer is second leading cancer killer in the United States, and ignoring it won’t keep it away. Together, cancers of the colon and rectum are among the most common cancers in the United States. They occur in both men and women and are most often found among people who are over the age of 50.
To address this topic, HealthLink is presenting a 2-part article on colorectal cancer. Part 1 focuses on risk factors and screening for prevention, while Part 2 discusses diagnosis and treatment.
Who's at Risk for Colorectal Cancer?
The diagnosis of cancer of the colon or rectum, also called colorectal cancer, raises many questions that need accurate, understandable answers. The colon and rectum are parts of the body's digestive system; together they form a long, muscular tube called the large intestine (also called the large bowel). The first 6 feet of the large intestine are called the colon; the last 8-10 inches are the rectum. Cancer that begins in the colon is called colon cancer, and cancer that begins in the rectum is called rectal cancer. Cancers affecting either of these organs may also be called colorectal cancer.
The exact causes of colorectal cancer are not known. However, studies show that the following risk factors increase a person's chances of developing colorectal cancer:
- Age. Colorectal cancer is more likely to occur as people get older. This disease is more common in people over the age of 50. However, colorectal cancer can occur at younger ages, even, in rare cases, in the teens.
- Diet. Colorectal cancer seems to be associated with diets that are high in fat and calories and low in fiber. Researchers are exploring how these and other dietary factors play a role in the development of colorectal cancer.
- Polyps are benign growths on the inner wall of the colon and rectum. They are fairly common in people over age 50. Some types of polyps increase a person's risk of developing colorectal cancer. A rare, inherited condition called familial polyposis causes hundreds of polyps to form in the colon and rectum. Unless this condition is treated, familial polyposis is almost certain to lead to colorectal cancer.
- Personal medical history. Research shows that women with a history of cancer of the ovary, uterus, or breast have a somewhat increased chance of developing colorectal cancer. Also, a person who has already had colorectal cancer may develop this disease a second time.
- Family medical history. First-degree relatives (parents, siblings, children) of a person who has had colorectal cancer are somewhat more likely to develop this type of cancer themselves, especially if the relative had the cancer at a young age. If many family members have had colorectal cancer, the chances increase even more.
- Ulcerative colitis is a condition in which the lining of the colon becomes inflamed. Having this condition increases a person's chance of developing colorectal cancer.
Having one or more of these risk factors does not guarantee that a person will develop colorectal cancer, but it does increase the chances. People may want to discuss their risk factors with their health care provider, who may be able to suggest ways to reduce their chances of developing colorectal cancer and plan an appropriate schedule for checkups.
Screening Tests Can Find Early Signs of Cancer
People who have any of the risk factors described above should ask a doctor when to begin checking for colorectal cancer, what tests to have, and how often to have them. The doctor may suggest one or more of the tests listed below. These tests are used to detect polyps, cancer, or other abnormalities, even if a person does not have symptoms. Your health care provider can explain more about each test.
- A fecal occult blood test (FOBT) is a test used to check for hidden blood in the stool. Sometimes cancers or polyps can bleed, and FOBT is used to detect small amounts of bleeding.
- A sigmoidoscopy is an examination of the rectum and lower colon (sigmoid colon) using a lighted instrument called a sigmoidoscope.
- A colonoscopy is an examination of the rectum and entire colon using a lighted instrument called a colonoscope.
- A double contrast barium enema (DCBE) is a series of x-rays of the colon and rectum. The patient is given an enema with a solution that contains barium, which outlines the colon and rectum on the x-rays.
- A digital rectal exam (DRE) is an exam in which the doctor inserts a lubricated, gloved finger into the rectum to feel for abnormal areas.
Steps You Can Take Now To Protect Your Health
Researchers have discovered that changes in certain genes (basic units of heredity) raise the risk of colorectal cancer. Individuals in families with several cases of colorectal cancer may find it helpful to talk with a genetic counselor. The genetic counselor can discuss the availability of a special blood test to check for a genetic change that may increase the chance of developing colorectal cancer. Although having such a genetic change does not mean that a person is sure to develop colorectal cancer, those who have the change may want to talk with their doctor about what can be done to prevent the disease or detect it early.
If you are 50 years old and have not been screened, talk to your doctor about having a screening test for colorectal cancer. Discuss the screening options that are right for you. Do not wait for symptoms.
Symptoms to Watch For
If you have any of the following symptoms, discuss them with your doctor. Only he or she can determine if cancer or other conditions are causing the symptoms. Common signs and symptoms of colorectal cancer include:
- A change in bowel habits
- Diarrhea, constipation, or feeling that the bowel does not empty completely
- Blood (either bright red or very dark) in the stool
- Stools that are narrower than usual
- General abdominal discomfort (frequent gas pains, bloating, fullness, and/or cramps)
- Weight loss with no known reason
- Constant tiredness
- Vomiting
These symptoms may be caused by colorectal cancer or by other conditions. It is important to check with a doctor to determine their exact cause and to begin treatment as needed.
Ask about colorectal cancer screening even if your doctor doesn’t mention it. Don’t feel uncomfortable about asking questions: bring a list with you and have it handy for your discussion. Take notes to help you remember important points; ask for further explanation if there is anything you don’t understand. Ask your doctor for brochures or other materials on colorectal cancer to take with you.
The National Cancer Institute supports and conducts research on the causes and prevention of colorectal cancer. Research shows that colorectal cancer develops gradually from benign polyps; their early detection and removal may help to prevent the disease. Studies are looking at smoking cessation, use of dietary supplements, use of aspirin or similar medicines, decreased alcohol consumption, and increased physical activity to see if these can prevent colorectal cancer. Some studies suggest that a diet low in fat and calories and high in fiber can help prevent colorectal cancer.
Research has led to real progress against this increasingly treatable disease, with a lower chance of death and an improved quality of life for the people who have it. Whatever your risk factors may be, leading a generally healthy lifestyle and seeking regular screening will be among the best preventive actions you can take to reduce your chances of being affected by colorectal cancer.
This article includes information from:
Article Created: 2002-03-12
Article Updated: 2002-03-28
Each year, Medical College of Wisconsin physicians care for more than 180,000 patients, representing nearly 500,000 patient visits. Medical College physicians practice at Children's Hospital of Wisconsin, Froedtert Memorial Lutheran Hospital, the Milwaukee VA Medical Center, and many other hospitals and clinics in Milwaukee and southeastern Wisconsin.
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