Colon Cancer

Colon cancer is the growth of malignant tumors in the lower intestinal tract, which includes the colon, rectum, and appendix. Majority of colon cancers also affect the rectum, so the terms “colorectal cancer” and “bowel cancer” are more commonly used. There are five main types of colon cancer:

  • Adenocarcinomas. These occur in the surrounding glands and account for 90 to 95% of colorectal cancers. There are two subtypes: mucinous and signet ring cell. The latter is relatively rare, occurring only in 0.1% of cases.
  • Leiomyosarcomas.  These arise from the smooth muscle of the bowels. Less than 2% of colorectal cancers are leiomyosarcomas, but they are more likely to spread to other organs than other types.
  • Lymphomas. Bowel lymphomas usually originate in the rectum rather than the colon, but the colon is more likely to catch non-Hodgkins lymphoma from other parts of the body.
  • Melanomas. Most melanomas start from other organs and spread to the colorectal area. It accounts for less than 2% of colorectal cancers.
  • Neuroendocrine tumors. Neuroendocrine tumors are as classified into aggressive and indolent subtypes. Aggressive tumors include small and large cell tumors, while indolent tumors consist of carcinoid growths.

Colon Cancer Stastistics In The USA

Colon and rectal cancers are the fifth most common cancer in the US, according to the National Cancer Institute. In 2007, 112,340 cases of colon cancer and 41,420 rectal cancers are expected, with a combined death rate of 52,180.

Causes And Diagnosis Of Colon Cancer

Most colon cancers arise from mushroom-shaped growths called polyps, which are usually harmless. It is not known what causes them to become malignant, but studies show that age, alcohol consumption, smoking, poor diet, and lack of physical activity can greatly increase one’s risk. People with a family history of colon cancer are also predisposed to the disease.

The most common diagnostic procedure is colonoscopy, wherein a thin, lighted tube is inserted into the rectum to check for polyps. However, not all bumps indicate cancer, and a biopsy is usually performed to confirm the diagnosis. The doctor may also check for blood in the stool through a stool DNA testing or a fecal occult blood test (FOBT).

Symptoms Of Colon Cancer

Many patients do not exhibit symptoms until the advanced stages, which is why doctors encourage periodic bowel screenings. Also, the closer the tumor is to the anus, the more visible the symptoms will be. Common indicators of colon cancer include bowel habit changes (frequency, quality and consistency), blood, mucus, or tar in the stools, and bowel obstruction. These may be accompanied by common conditions such as anemia, weight loss and anorexia, and asthenia (weakness).

Treatment Of Colon Cancer

Colon cancer is usually curable when detected early, but a complete cure is less likely in the advanced stages. If the tumor develops in a polyp, removing the polyp in the early stages usually promises a complete cure. Advanced colon cancer may be treated by removing part of the colon, and either reconnecting the remaining ends or diverting the colon to the side of the abdomen. In the latter case, the doctor cuts an opening through the skin for stools to pass through, and attaches a special colostomy bag to hold the stools.

When the cancer has spread to other parts of the body (metastasized), a complete recovery is unlikely, although surgery may be performed to prevent further spreading. Surgery is usually followed by chemotherapy or radiotherapy to remove remaining cancer cells and prevent a recurrence. Other alternative cancer treatment methods may be used to treat colon cancer.

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