What is colorectal cancer?
How common is colorectal cancer?
Who is at risk?
How does it start?
What are the symptoms?
How is it diagnosed?
How is colorectal cancer treated?
What is a Medical Oncologist?
Can colorectal cancer be prevented?

What is colorectal cancer?

Colorectal cancer develops in the colon, the first and longest section of the large bowel; or the rectum, the final six inches of the large bowel. The colon has four sections:

  • the ascending colon - begins where the small bowel attaches and extends upward on the right side of the abdomen
  • the transverse colon - goes across the body to the left side
  • the descending colon - continues downward on the left side
  • the sigmoid colon - the S-shaped colon which joins the rectum, which in turn joins the anus, or the opening where waste (fecal) matter passes out of the body.

The colon and rectum have several layers of tissue. Colorectal cancers start in the innermost layer and can grow through some or all of the other layers. The penetration of the cancer through these layers will dictate the course and severity of the cancer.

It is believed that colorectal cancers begin as polyps, also known as adenoma, and develop slowly over a period of several years. Once a cancer forms in these polyps, instead of growing only into the center of the lumen of the colon or rectum, it will also grow into the wall of these organs. Cells from the tumor can then break away and spread through the bloodstream or lymph system to other parts of the body. There, they may form "colony" tumors. This process is called metastasis.

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How common is colorectal cancer?

Colorectal cancer is the third most common cancer in the United States, striking approximately 150,000 people annually and causing nearly 60,000 deaths. It accounts for about 11% of all cancer deaths. That figure is staggering when you consider the disease is potentially curable if diagnosed in the early stages.

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Who is at risk?

Though colorectal cancer may occur at any age, more than 90% of the patients are over age 40, at which point the risk doubles every ten years. In addition to age, other high risk factors include a FAMILY history of colorectal cancer and polyps (up to 50% of all colorectal cancers have a strong inherited component) and a PERSONAL history of ulcerative colitis, colon polyps or cancer of other organs, especially of the breast or uterus. Additional risk factors include: diet, less-than-moderate exercise, and obesity. The disease afflicts women and men equally.

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How does it start?

It is generally agreed that nearly all colon and rectal cancer begins in benign polyps. These premalignant growths occur on the bowel wall and may eventually increase in size and become cancerous. Removal of benign polyps is one aspect of preventive medicine that really works.

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What are the symptoms?

The most common symptoms are rectal bleeding and changes in bowel habits, such as constipation or diarrhea. (These symptoms are also common in other diseases so it is important you receive a thorough examination should you experience them.) Abdominal pain and weight loss are usually late symptoms indicating possible extensive disease.

Unfortunately, many polyps and early cancers fail to produce symptoms. Therefore, according to the American Cancer Society, it is important that your routine physical include a colorectal cancer detection procedure once you reach age 50. Those detection methods are a digital rectal exam and a chemical test of stool for blood (fecal occult blood test-FOBT). A sigmoidoscopy (the inspection of the lower bowel with a lighted tubular instrument), a colonoscopy (the inspection of the full colon with a lighted tubular instrument), or a double barium enema should be part of routine physical check-ups.

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How is colorectal cancer diagnosed?

It is widely accepted that the overwhelming majority of colorectal tumors arise from polyps in the colon and rectum. Polyps are abnormal projections of tissue that protrude inside the bowel. They are most frequently found by diagnostic/screening procedures; sigmoidoscopy for the lower intestine, or colonoscopy for the entire intestine. If polyps are found during these procedures, they are removed and sent to a pathology laboratory for sectioning and microscopic examination. If the pathology report confirms the presence of cancerous cells, surgery is scheduled to remove the tumor and surrounding area of the colon. At the same time, lymph nodes from the surrounding area are also usually removed for examination to determine if the cancer has begun to spread (metastasized) into the lymph system.

For more information about the diagnosis options, click here.

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How is colorectal cancer treated?

Surgery, radiation therapy and chemotherapy are methods used to treat colorectal cancer, depending on the stage of the disease. Colorectal cancer requires surgery in nearly all cases. Radiation and chemotherapy are sometimes used in addition to surgery. Reoccurrence rates can be decreased with earlier intervention. In fact, colorectal cancers that are diagnosed at an early stage have five-year survival rates as high as 95%.

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What is a colon and rectal surgeon?

Colon and rectal surgeons are experts in the surgical and non-surgical treatment of colon and rectal disorders. They have completed specialized training in the treatment of colon and rectal diseases in addition to full training in general surgery. Colon and rectal surgeons treat benign and malignant conditions, perform routine screening examinations and surgically remove tumor growths when necessary.

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What is a Medical Oncologist?

A medical oncologist is a doctor who specializes in the use of medications (such as chemotherapy, hormones and analgesics) for the management of invasive cancer. To become certified as an oncologist, a candidate must first graduate from an accredited medical school before entering into training as a specialist (such as internist, pediatrician) and then choose a subspecialty such as medical oncologist or surgical oncologist, for example. There are several oncology specialties and subspecialties. The medical oncologist will discuss how each treatment is administered and the length of treatment, the effectiveness of each treatment according to data from clinical trials, and the potential side effects of each.

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Can colorectal cancer be prevented?

Although the exact cause of most colorectal cancer is unknown, it is possible to prevent the majority of colon cancers. Following screening guidelines can lower the number of cases of the disease by detecting and removing polyps that could become cancerous, and can also lower the death rate from colorectal cancer by finding disease early, when it is high treatable.

Most cancers develop from polyps so removing them can lower a person’s risk by preventing colorectal cancers before they have a chance to form.

People can take control and reduce their cancer risk by making some positive life style changes:

  • Diet – Cut down on red meats and increase intake of fruits and vegetables
  • Physical activity – even small amounts of exercise on a regular basis can have a major impact, at least 30 minutes a day or even walking 3 hours a week.
  • Maintain a healthy weight.
  • Limit intake of alcoholStop smoking.
  • Increase calcium intake through supplements or low-fat diary products


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