What is the colon and how does it work within the digestive system?
The colon, also called the large bowel or large intestine, is the last section of the digestive tract. It is five to six feet long, the last eight to 10 inches of which is called the rectum. After food is digested in the stomach and nutrients are absorbed in the small intestine, solid wastes from this process move into the colon, where they remain usually for a day or two until they are passed out of the body.
What is colorectal cancer?
Sometimes the body’s cells fail to grow, divide and reproduce in a healthy, orderly way, thus producing too much tissue and forming a tumor. These tumors can be benign, which are not cancerous, or malignant, which are cancerous and can spread to other parts of the body.
Who develops colorectal cancer?
Although there’s a general misconception that it’s mainly a male disease, both men and women develop colorectal cancer with almost equal frequency. In fact, more women over the age of 75 die of colorectal cancer than of breast cancer. There are regional differences of the disease’s incidence and mortality throughout the country, with the highest rates occurring in the Northeastern United States. In addition, survival rates in African Americans are lower than in the general population.
Who is considered particularly at risk for the disease?
There are two basic levels of at-risk populations: average-risk and high-risk. Generally, anyone over the age of 50 is considered at average risk, with the incidence of colorectal cancer approximately doubling with each decade of a person’s life. High-risk groups include those with either a personal or a family history of colorectal neoplasia (cancer or polyps), and those with an inflammatory bowel disease, such as ulcerative colitis or Crohn’s disease.
How does the disease progress?
As with all cancers, there are stages of disease progression, as well as expected survival rates for these different stages. The importance of screening and early detection becomes evident when looking at the following stages of colorectal cancer:
Polyps without cancer that have been removed – 100% cure
Stage I Polyps with cancer on the wall of the colon – a 95 percent chance for a five-year survival.
Stage II Metastasis, or spreading, to tissue around the colon – a 60 percent chance for a five-year survival.
Stage III Metastasis to lymph nodes around the colon – a 35 to 60 percent chance for a five-year survival.
Stage IV Metastasis to other parts of the body – a 3 – 7 percent chance for a five-year survival.
What screening techniques are used to detect polyps early?
Because colorectal cancer, unlike many other types of cancer, exists in a readily detectable, easily curable state for a long time, there is a greater chance it can be detected with screening. Many safe and highly accurate tests are available to detect an early cancer or a colonic polyp and significantly reduce deaths from colorectal cancer.
A fecal occult blood test (FOBT) screens for invisible amounts of blood in the stool by testing small samples of stool for three consecutive days. This test can be done at home upon physician recommendation.
A flexible sigmoidoscopy examines the inner lining of the rectum and the last two feet of the colon where the majority of cancers and polyps develop. An endoscope, a thin, flexible tube with a light on the end, is used to identify any polyps or cancer. The test is not painful, does not require the use of any anesthesia, and usually is performed in a doctor’s office.
A colonoscopy examines the entire inner lining of the colon. An endoscope, a thin, flexible tube with a light on the end, is used to identify any polyps or cancer. Generally polyps can be removed during colonoscopy using special snares and coagulation techniques. The test is not painful, does require sedation and can be performed in a hospital lab or in an endoscopy ambulatory surgery center.
A barium X-ray is another screening method. With this procedure, a patient first is given a barium enema, then air is introduced into the colon, and X-rays are taken to identify any irregularities.
Virtual Colonoscopy (scan of the colon) has been introduced recently with encouraging results.
What does surveillance mean?
High-risk patients and those who receive positive results from screening tests will be recommended for a surveillance procedure that will take a closer look at the colon. A colonoscopy often is the preferred diagnostic method, because it is highly accurate, well-tolerated and adequately safe. It is similar to the flexible sigmoidoscopy, but it provides a view of the entire colon and allows the physician to perform a biopsy or polypectomy (removal of the polyps) in a single procedure. A colonoscopy typically is performed in a hospital or ambulatory surgery center, and the patient is given a sedative to eliminate any discomfort.
What are the recommended guidelines for screening and surveillance?
Groups such as the American Cancer Society, the National Cancer Institute, and the World Health Organization’s U.S. Collaborating Center for the Prevention of Colorectal Cancer have issued guidelines for screening and surveillance procedures. Essentially, these guidelines call for screening of all average-risk people with annual fecal occult blood tests and flexible sigmoidoscopy every three to five years. For average or high-risk individuals, periodic colonoscopy is often recommended.
How is colorectal cancer treated?
Most colorectal polyps are removed easily during colonoscopy without the need for surgery. Treatment of early-stage cancer usually requires surgery to remove the portion of the colon containing the tumor. A permanent colostomy, an artificial opening to remove waste from the body, is required only in the few cases where the cancer is located at the very end of the bowel in the rectum. Treatment of later stages of the disease is less successful and often requires radiation therapy or chemotherapy, in addition to surgery.
What causes the disease?
Its exact cause is unknown, but it appears to be caused by both inherited and environmental factors. Some data suggest that diets high in fat (red meat, fried foods, high-fat dairy products) increase the chances of developing the disease, while diets high in fiber (fruits, vegetables, whole grains) appear to reduce the risk. The effects of a number of other substances, such as minerals, vitamins and drugs, are currently under study.
Genetic factors may determine a person’s susceptibility to colorectal cancer, whereas dietary and other environmental factors may determine which at-risk individuals actually go on to develop the disease.
What are the symptoms of a digestive health problem?
Several symptoms may appear with an illness of the colon. While not necessarily indicative of colorectal cancer, it is important to consult with a physician if these symptoms persist longer than two weeks. Symptoms include:
Diarrhea or constipation
Blood in or on the stool
General stomach discomfort (bloating, fullness, cramps)
Frequent gas pains
Feeling that the bowel does not empty completely
Loss of weight with no known reason
Almost all cases of colorectal cancer – also commonly referred to as colon cancer – begin with the development of benign colonic polyps. These polyps, for reasons still unknown, often turn into cancer, yet they rarely produce noticeable symptoms. Fortunately, several screening methods can be used to detect polyps before they become cancerous, and removal of the polyps can prevent the onset of colorectal cancer. In fact, this disease is one of the most preventable and curable cancers when detected at an early stage.
How common is this type of cancer?
Colorectal cancer is the second-leading cause of death from cancer, behind lung cancer, in the United States. The National Cancer Institute estimates that more than 65,000 people will die this year of colorectal cancer in the United States. Moreover, estimates predict more than 160,000 new cases of the disease annually and 80 to 90 million people considered at risk because of age or other factors.
Will a patient be referred to a specialist?
Usually, a primary care physician will perform screening tests, such as the flexible sigmoidoscopy. In many instances a gastroenterologist will perform the test. (Fecal occult blood tests can be self-administered at home.) If the tests are positive, the patient will be referred to a specialist – typically either a gastroenterologist or gastrointestinal surgeon – for examination of the entire colon through colonoscopy. If a polyp or cancer is found, it also will be treated by a specialist as described above.