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 is an abnormal gene 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.
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 conditions, such as hereditary polyposis, lead to colon cancer 100 percent of the time. Persons living and eating in Western society 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 a 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, changes into certain compounds termed carcinogens. These compounds cause colon cancer in some animals. When residents in other parts of the world 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 Western society. So diet 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:
- The Ordinary Polyp — Most 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 often no hereditary incidence.
- 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.
- Lynch Disorder — This hereditary condition is more common. In it there is a strong tendency for adenoma type polyps to develop in blood relatives; sisters, brothers, aunts, uncles and children. It is in this condition that more polyps are seen and at an early age. Polyps and even cancer can occur in the 30’s and even 20’s. So a family history of this type warrants surveillance on other, especially younger blood relatives.
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:
- Medical history — The patients medical history will identify the present of risk factors for colon polyps and cancers.
- Stool exams to detect occult blood — Colon cancers and large polyps release minute quantities of blood; therefore, examination of the stool for occult blood is an important exam.
- Sigmoidoscopy — This procedure is the visual examination of the inside of the rectum and sigmoid colon. During a sigmoidoscopy only the last 1 to 2 feet of the colon is examined. Using a lighted, rigid or flexible tube, allows the direct detection of colon tumors.
- Colonoscopy — This procedure is the visual examination of the large intestine (colon). It is 5-6 feet long. The colon begins in the right-lower abdomen and looks like a big question mark as it moves up and around the abdomen, ending in the rectum. Physicians perform this when any of the above three detection methods suggests a problem. The exam is usually done under sedation with a long colonoscope. It is really the definitive test since colon polyps can be discovered and removed at the same time.
- Barium Enema — This x-ray exam is an older, at times still useful, exam. Barium is injected into the colon and x-rays are taken which then can outline the shadows of polyps and cancer. Polyps can not be removed by this technique.
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 colonoscopy, which allows the physician to visualize the inside of the colon. Biopsy equipment and snares (wire loops) are passed through the scope and with electrical heat (electrocautery), are used to remove polyps and small tumors. This procedure is performed in the outpatient setting under sedation.
In Summary
Cancer of the colon is a serious but readily detected malignancy. In addition, early detection promises a particularly high chance of survival. Most colon cancers start as polyps, which can usually be removed with an outpatient procedure. Today, much information is available to significantly reduce the risk of this disease.