|The causes of colon cancer|
Tuesday, 02 July 2013 00:00Written by Vonda Sines
The list of public figures whose lives it has claimed is long indeed. Among them: actor Jack Lemmon, legendary Green Bay Packers football coach Vince Lombardi, actresses Elizabeth Montgomery and Audrey Hepburn, evangelist Tammy Faye Messner and former White House press secretary Tony Snow.
It's the second-deadliest form of cancer in the United Sates, most often striking patients at least 40 years old.
Cancer of the colon - which makes up the upper four to five feet of the large intestine - happens when previously healthy cells somehow become altered. While healthy cells develop and divide in an orderly pattern to maintain normal body functioning, sometimes their growth gets way out of control, according to the Mayo Clinic.
Even when the body needs no new cells, the existing ones continue to divide. This extra growth has been targeted as a potential cause for precancerous cells to be produced in the lining of the colon. The amount of time required for them to turn into colon cancer has been estimated as up to several years.
The Mayo Clinic states that as is the case with most types of cancer, the exact cause of this disease officially remains unknown. Sometimes precancerous cells cluster as polyps that grow out of the wall of the large intestine into the tube through which food passes during digestion. They're often shaped as mushrooms. Another type of precancerous growth - the nonpolypoid lesion - can occur as flat or even recessed into the wall of the colon. While they're more difficult to locate, they're less common than other growths.
Three common types of polyps occur in the colon:
1. Adenomas: Physicians usually remove them during a screening procedure such as a colonoscopy or a flexible sigmoidoscopy because they can potentially cause colon cancer.
2. Hyperplastic polyps: They rarely, if ever, represent a risk factor for colon cancer.
3. Inflammatory polyps: Some of them can evolve into cancer. Since they sometimes follow a flare of ulcerative colitis, having this disease increases a patient's risk of contracting colon cancer.
According to Medicinenet.com, doctors are positive that colorectal cancer is not contagious. Researchers now suggest that a diet high in fat predisposes some patients to colon cancer since the rate of contracting this disease is much lower in countries with lower fat than amounts typically found in the American diet. They believe that the breakdown products of metabolizing fat cause cancer-causing chemicals known as carcinogens to form in the body.
A patient's genetic background is also a primary factor in determining his or her risk for developing colon cancer. A study of first-degree relatives of colon cancer patients revealed that their lifetime risk of developing this type of malignancy is 18 percent - a threefold increase over the risk of the general American population.
Medicinenet.com points out, however, that 80 percent of colon cancers arise in patients with no family history of the disease. About 5 percent of cases of colon cancer have been linked to hereditary colon cancer syndromes. These are disorders that cause afflicted members of a family to inherit cancer-causing genetic defects from either one or both of their parents.