Colon Cancer

April 22nd, 2013 by Eduardo Krajewski, MD, FACS, FASCRS

It is the third most common cancer in the United States, and worldwide nearly half a million people die from it every year. The good news is that colon cancer is preventable and treatable, but early detection is critical.

What is colon cancer?

Cancers are collections of normal cells that have been changed or mutated. These mutated cells grow out of control and behave differently than normal cells. Colon cancer is a cancer of the large intestine. Most of the time colon cancers start out as small non-cancerous polyps.

What are the symptoms of colon cancer?

Colon cancer almost always starts without symptoms. In fact, once symptoms have developed the disease is often advanced. Some symptoms of colon cancer can be:

  • Blood in the stool
  • Change in bowel habits, persistent diarrhea or constipation
  • Abdominal pain
  • Weakness, fatigue
  • Unexplained weight loss

What causes colon cancer?

In the majority of cases the exact cause of the cancer is unknown; however, there are some known risk factors. These are:

  • Older age
  • Male gender
  • Diet with high levels of fat, alcohol or red meat
  • Obesity
  • Smoking
  • Lack of physical activity
  • Inflammatory bowel disease

In a small percentage of cases there is a genetic link. Familial adenomatous polyposis and Lynch syndrome are the most common colorectal cancer syndromes that run in families.

How is colon cancer diagnosed?

The cancer is usually detected at first on screening or if symptoms develop. The definitive diagnosis is made by colonoscopy. The doctor takes a biopsy during this procedure, and the tissue is sent to a lab where it is studied under a microscope to look for cancer cells.

Once the diagnosis is made, the cancer must be staged. Staging means determining how far the cancer has advanced. Pre-treatment staging is determined by:

  • Physical exam
  • CT scan of the abdomen, pelvis and chest

How is colon cancer treated?

The treatment of colon cancer depends on the stage. For localized tumors, surgery is often recommended and can even be curative. For very small cancers, removal can often be accomplished with colonoscopy or minimally invasive laparoscopy. For larger cancers, an open surgery must be done, and a segment of the colon might have to be removed as well.

Chemotherapy also plays an important role in the treatment of some colon cancers. For example, in persons where the cancer has spread to the lymph nodes, chemotherapy has been shown to reduce the risk of both death and disease recurrence by about 30%.

Oxyplatin is the most commonly used chemotherapeutic agent. This therapy carries the risk of serious side effects like inflammation of the lining of the digestive tract, vomiting, diarrhea, fever, hair loss, and heart toxicity. Most of the side effects resolve when the therapy is stopped.

Sometimes the cancer has metastasized, that is, spread to other organs. The most common sites affected are the liver and the lung. However, in these cases there are still treatment options. For example, the surgeon and the oncologist might recommend surgically removing the spread tumor and then giving chemotherapy after the surgery.

What are the survival chances?

Again, this depends upon the stage. For example, Stage I cancers have a five year survival between 90-100%. Once the cancer has spread to lymph nodes, the five year survival rate falls to about 40%. For those with disease that has spread to other organs the survival rate is only about 5%


Colon cancer is a very common cancer and causes many thousands of deaths every year. The key to reducing the death toll is early detection. Screening can detect disease at an early and curative stage. Once symptoms develop, the chances for survival go way down.

Ask your doctor about colon cancer screening. It just might save your life.

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