Colon polyps are abnormal growths that develop from the inner lining of large intestine. Sigmoid colon and rectum are end part of large intestine. Cancer of colon and rectum is the third most common cause for cancer deaths in United States. Polyps are nothing but tumors and they develop due to genetic mutation in cell lining of colon.
Although most colon polyps are non cancerous, some may have tendency to become malignant, especially the adenomatous type. Other type called hyperplastic polyp usually do not carry the risk of becoming malignant. Larger polyps have high malignant potential.
Anyone can suffer from malignant colon polyps, but it is more prevalent among people over the age of 60. Family history, smoking, diet consisting red meat, inflammatory bowel disease are some of the risk factors for development of colon cancer.
Considering the potential risk of even a benign polyp becoming malignant, doctors generally remove the polyp and send it for laboratory test to rule out malignancy.
What Causes Cancerous Colon Polyps?
Colon polyps develop from the inner layer of large intestine. They may be anywhere in the colon, but most of them are in last part of colon and rectum.Colon polyps as any other benign or malignant growth develop when the cells of the lining abnormally multiply or in medical term they ‘mutate’. Mutation may occur since birth or after birth.
Colon polyps in majority of cases are not cancerous, but some of them have potential to become malignant later on. Especially large colon polyps are prone to become malignant. Most colon cancer originates from polyps present in its inner lining. Colon polyps can develop in males and females equally.
People having polyps in colon should always be investigated for malignancy as the vulnerability increases with age.Out of the two types of colon polyps, an adenomatous polyp has increased risk of developing into colon cancer. Following are the risk factors:
- People with inflammatory bowel disorders such as ulcerative colitis, and Crohn’s disease.
- Family history of colon cancer and malignant colon polyps.
- Eating excess of red meat or processed meat.
- Heavy intake of alcohol.
- Cigarette smoking
Symptoms Of Malignant Colon Polyps
Majority of colon polyps do not present with any symptoms and they are spotted accidentally while screening for some other conditions. If symptoms occur they are as follows:
- Blood in stool. It occur when there is bleeding from the polyp or from the stalk of the growth.
- Black colored stool or black colored blood if bleeding occurs from polyps from higher up region of colon such as from cecum or ascending colon.
- Anemia if bleeding from polyp is slow.
- Alternate constipation and diarrhea.
- Unexpected weight loss.
- Loss of appetite.
- Mild to moderate pain in abdomen.
- Large polyp inside the colon can cause intestinal obstruction, but it is rare.
Treatment For Malignant Colon Polyps
If polyp in colon or rectum is detected, the first thing that needs to be done is to remove it and send the collected material for laboratory examination. Colon polyps are removed with the help of colonoscope. Once the polyp structure is determined microscopically and with histological test, the doctor is able to know if it is malignant or has increased risk of malignancy.
Large polyps will require to be removed with surgical procedure. In certain cases a part of colon has to be resected. Large numbers of lymph nodes are also removed from the abdomen during the surgery. In advanced cases where the cancer has spread to distant organs, chemotherapy and radiation may be helpful.