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Colon Polyps and Cancer

Colon Polyps and Cancer

Cancer of the colon is a major health problem in the United States. It ranks as a leading form of cancer, along with lung and breast cancer. Importantly, colon cancer is also one of the most curable forms of cancer. When detected early, more than 90 percent of patients can be cured.

This disease begins in the cells that line the colon. There now is strong medical evidence that there are abnormal genes for colon polyps and cancer that can be passed from parent to child. The genes within each cell are the hereditary structures that tell the cell what it should do. It is becoming increasingly clear that certain of these genes control the growth of the cells on the lining of the colon. When these controlling genes are absent there is a tendency to grow polyps. The cells in the polyp eventually become uncontrolled and turn into a cancer. Colon cancer also can develop from other conditions, such as ulcerative colitis, a chronic inflammation in the colon.

What is a Colon Polyp?

A polyp is a growth that occurs in the colon and other organs. These growths, or fleshy tumors, are shaped like a mushroom or a dome-like button, and occur on the inside lining of the colon. They may be as small as a tiny pea or larger than a plum. It is important to note that while colon polyps start out as benign tumors, some polyps, in time, become malignant. In fact, the larger the polyp, the more likely it is to contain cancer cells. In most cases, it is a polyp called an adenoma polyp that develops into colon cancer.

What are the Risk Factors For Developing Colon Polyps and Cancer?

  • Family history of polyps, cancer and especially, colon cancer
  • Western civilization and diet 
  • Being over 40 years of age 
  • History of breast cancer 
  • Ulcerative colitis

An individual whose parents, brothers or sisters have colon cancer is at increased risk. In addition, certain unusual conditions, such as hereditary polyposis, lead to colon cancer 100 percent of the time. Persons living and eating in Western societies are exposed to certain factors that are detrimental to the bowel. Medicine is just beginning to learn about these. Also, females who have had genital or breast cancer are at an increased risk of developing colon cancer. Ulcerative colitis, after a long time, also can lead to colon malignancy.

Why Do Polyps Form?

As noted above heredity is probably the most important factor. The absence of a controlling gene within the cells is most likely a necessary event.

Other facts are known. Rural residents in Africa and India rarely develop colon polyps or cancer. Their diets are high in unprocessed grains (bran) and low in meat. Diets that are high in bran and roughage produce bulky stools that have a lower bacteria count. Further, it is known that animal fat in meat, when broken down by the body's intestinal juices, may change into certain compounds termed carcinogens. These compounds cause colon cancer in laboratory animals. When residents in developing countries eat a Westernized diet of meat, low roughage and refined grains, over time they develop the same incidence of colon polyps and cancer as people living in the Western world. So diet probably plays an important role in causing colon cancer.

Three Categories of Polyps

Enough is now known about polyps that physicians generally place patients in one of three categories. In each of these the end result is an adenoma type polyp:

  1. The Ordinary Polyp-Most sporatic polyps occur between the ages of 40 and 60. There may be only one or two present and they may take ten years or more to develop into a cancer. There is a hereditary link.
  2. Familial Polyposis-This is a true hereditary condition in which the entire colon is studded with hundreds, even thousands of polyps. They begin at a very early age even under ten years old. And virtually every patient will eventually develop colon cancer. The only known preventive treatment is removal of the colon. Fortunately, the condition is not common.
  3. Lynch Syndrome-Dr. Lynch first described this hereditary disorder. It is more common than familial polyposis and less so than the ordinary polyp. In it there is a strong tendency for adenoma type polyps to develop in close blood relatives such as sisters, brothers, aunts, uncles and children. More polyps are seen and at an early age. Polyps and even cancer can occur in the 30's and even 20's. In some families there is an increased incidence of breast, ovarian, and other cancers. So a family history of this type warrants very close surveillance of all direct blood relatives.

Detection

The key to early detection of colon polyps and cancer is the concern and willingness of each person to seek medical attention from a physician. The physician will perform the following:

  1. Medical history-The patient's medical history will identify the presence of risk factors for colon polyps and cancer.
  2. Stool exams to detect occult (hidden) blood-Colon cancers and large polyps release minute quantities of blood; therefore, examination of the stool for occult blood is an important exam.
  3. Sigmoidoscopy-A visual exam of the rectum and lower colon, using a lighted, rigid or flexible tube, or endoscope, allows the direct detection of colon tumors.
  4. Colonoscopy-This procedure examines the entire 5-6 foot long colon. Physicians perform it when any of the above three detection methods suggests a problem. The exam is usually done under sedation. It is really the definitive test since colon polyps can be discovered and removed at the same time.
  5. Barium Enema-This x-ray exam is an older, at times still useful, exam. Barium flows into the colon and x-rays are taken which then can outline the shadows of polyps and cancer. Polyps cannot be removed by this technique.
  6. Future tests-It is possible that a blood genetic test may become available to identify those individuals who are destined to develop colon polyps and cancer.

How are Polyps Removed?

Removal of colon polyps reduces the risk of subsequent development of cancer of the colon. Polyps are usually removed using a colonoscope, which allows the physician to visualize the inside of the colon. Biopsy equipment and snares (wire loops) are passed through the endoscope and, with electrical heat (electrocautery), remove polyps and small tumors. This procedure is performed in the outpatient setting under sedation.

Summary

Cancer of the colon is a serious but readily detected malignancy. Early detection promises a particularly high chance of survival. Most colon cancers start as polyps, which can usually be removed through a colonoscopic exam. Today, there is much that can be done to prevent and cure this cancer. The essential first step involves action by the patient.


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