Polyps are abnormal overgrowth of tissues, that protrude from the mucous membrane. Such growths may develop anywhere in the body, where there is mucous membrane. These abnormal growths are usually found in the uterus, cervix, nose, sinuses, urinary bladder, stomach, and colon. In case of colon, polyps are mostly found in elderly people. As per statistics, more than 50% of the elderly population (those above the age of sixty) will have at least one colon polyp. Most of the colon polyps are harmless, till they are small. While it cannot be said that all colon polyps can become cancerous, some of them may turn malignant with time and so, are removed as soon as they are detected. The chances of malignancy is decided on the basis of various factors like the type of colon polyp and its size.
So colon polyps are often associated with a risk of turning cancerous. It is a common fact that colon cancer is one of the leading causes of cancer-related deaths in both genders. So, it is very much important to get the condition diagnosed and treated at the earliest. Most of these polyps are asymptomatic, but possible symptoms of colon polyps include rectal bleeding, blood in stools, constipation, and/or diarrhea. Some people may experience pain too. Those with multiple and/or large polyps are more prone to develop such symptoms. In most cases, colon polyps are detected during routine colon cancer screening or colonoscopy.
Types of Colon Polyps
Colon polyps can either be sessile or pedunculated. If the mass of tissues is attached to the surface by a long, thin stalk, the polyp is categorized as pedunculated, whereas sessile ones lack stalks and develop on the surface itself, mostly as flat growths. Colon polyps are classified into different types, the most common among them being hyperplastic and adenomatous polyps.
Hyperplastic colon polyps are very small and are usually found in the rectum. These colon polyps carry a very low chance of turning malignant. However, it is difficult to differentiate this type from the other types during colonoscopy and so they are also removed and biopsied, in order to rule out the risk of colon cancer. It is said that even these polyps carry the risk of turning cancerous, if they grow larger in size. It has also been contented that hyperplastic colon polyps that develop on the right side of the colon have more chances of growing in size and turning malignant.
Adenomatous colon polyps are also commonly found and are associated with a higher risk of colon cancer. Most of them are benign and do not become malignant, but have the potential to turn cancerous in the long run. They are further classified into three types - villous, tubular and tubulovillous, as per the appearance and microscopic features. Among these three types, villous adenomas are more likely to become cancerous, while tubular ones are the least dangerous. If villous adenomas carry 40% risk, in case of tubulovillous ones, the risk is almost half or 20%. The same for tubular adenoma polyps is only 5%.
There is a third category named inflammatory colon polyps, that are mainly found in those with ulcerative colitis or Crohn's disease. Otherwise known as false polyps, such growths are said to be caused by inflammation of the colon wall. Usually, inflammatory colon polyps do not turn cancerous.
In short, the non-malignant colon polyps may turn cancerous at a later stage. So, once a colon polyp is detected, it is removed irrespective of the type, so as to avoid any risk of colon cancer. Colon polyps are common in people who are above the age of fifty, or who have a family history of colon cancer. It can also occur in people with relatives having polyps or in those who have had polyps before. Factors like, high-fat diet (especially those with red meat), regular and excessive cigarette smoking, and a diet that is low in fiber are said to be among the contributory factors for occurrence of colon polyps.
Tubular Adenoma Polyp
So, these polyps are the least dangerous among the three types of adenomatous colon polyps. Tubular adenoma polyps carry a very low risk of becoming cancerous. The more life-threatening colon polyp, called villous adenoma, is larger in size and is mostly found to be sessile. The villous adenoma is velvety in appearance with several finger-like projections, called villi on the epithelium, are generally found in the rectum.
A tubular adenoma polyp has a tube-like structure, with 75% of the epithelium arranged in a tubular fashion. Most of these polyps turn out to be non-cancerous, but the risk of colon cancer gets higher as these polyps grow. Most of these polyps are pedunculated and can be found anywhere in the colon, whereas the villous polyps mostly develop in the rectum. The third type, called tubulovillous colon polyps, are tubular with 25% to 50% of villous component. The tubular ones develop more villous components as they grow larger and may become sessile too. Such developments increase the risk of cancer in tubular adenoma polyps.
In short, the risk of colon cancer depends on the type of polyp to some extent only. The main factors that determine the chances of developing cancer, is the size of the polyp and the degree of abnormal cellular development (dysplasia). The larger they become, the greater the risk of colon cancer. It is advisable to remove the colon polyp, whether it is tubular adenoma colon polyp, villous polyp or any other colon polyp. This move helps cut down the chances of developing colon cancer at a later stage. Hence, a flexible sigmoidoscopy (once, every three years) is recommended for those who have passed the age of fifty. Other diagnostic methods used to detect colon polyps include colon X-rays, colonography, and colonoscopy. Those who have reached the age of forty, must go for a stool specimen test every year for ruling out the possibility of colon polyps. Above all, maintaining health with a balanced diet and a healthy lifestyle can help you prevent the occurrence of polyps to some extent.