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Colon and Rectal Cancer

What is colon or rectal cancer?

Colon or rectal cancer is a growth of abnormal cells in the colon or rectum. This growth of cells is called a malignant tumor (cancer). The colon and rectum are sections of the large intestine, which is also called the large bowel. The colon is the first part of the large bowel. It is nearly 5 feet long. The rectum is the last few inches of the large bowel. The rectum is at the end of the colon and just above the anus.


It is important to diagnose and treat colon or rectal cancer as soon as possible. If not treated, the cancer can spread through the bowel wall to lymph nodes and the bloodstream and to other parts of the body.


The large intestine is one of the 4 most common sites for cancer to occur. (The other 3 most common sites are the lungs, the breasts, and the prostate.)


Another name for this type of cancer is colorectal cancer.

How does it occur?

Cancer cells are abnormal cells that grow in an uncontrolled way. They can spread (metastasize) beyond where they start. Most colorectal cancers start from a type of polyp called an adenomatous polyp. Polyps are growths of extra tissue on the inside wall of the bowel.


Colorectal cancer is more common in countries where obesity is common, where the diet is high in fat and low in fiber, and where daily exercise is less common. It is not known how this combination of obesity, diet, and lack of exercise combine to increase the risk for colorectal cancer. Colon or rectal cancer usually occurs after age 50, but it can happen at any age.


You may have a greater risk of developing colon cancer if you:

  • have had colorectal cancer before
  • have colorectal polyps or inflammatory bowel disease, such as ulcerative colitis or Crohn's disease
  • have a parent, brother, or sister who has had colon cancer or colon polyps
  • have had uterine, ovarian, or breast cancer
  • eat a high-fat and low-fiber diet
  • smoke cigarettes

What are the symptoms?

At first there are no symptoms. When symptoms do occur they may include:

  • blood in bowel movements (stools)
  • diarrhea or constipation
  • feelings that the bowel does not empty completely
  • stools that are narrower than usual
  • gas pains or cramps or an unusual sense of fullness in the abdomen
  • feelings of tiredness all the time
  • unexpected weight loss

How is it diagnosed?

Your healthcare provider will review your symptoms and examine your abdomen and rectum. A sample of a bowel movement will be tested for blood. If you have seen blood in your stool or if your provider finds blood in your stool with a chemical test, you will be advised to have a procedure to examine the inside of the colon. The procedure, called a colonoscopy, lets your healthcare provider look at the inside of the colon and rectum. To do the procedure, your provider inserts a slim, flexible, lighted tube through your anus and looks at the inside of your colon and rectum. Your provider may remove a small piece of tissue that looks abnormal to test for cancer (a test called a biopsy). Colorectal cancer is common enough that colonoscopy after the age of 50 is recommended as a routine screening procedure.


Another test you might have is a double-contrast barium enema. In this procedure fluid that contains barium is put into your colon. X-rays are then taken that show the inside of your colon. If the X-ray images show a polyp or cancer, you will need to have a colonoscopy to get a sample of tissue (biopsy) for lab tests.


If cancer is found, tests may include more lab tests and scans to check for spread of the cancer to other parts of your body.

How is it treated?

Your healthcare provider will determine the stage (amount of spread) of the cancer. The treatment choices are based on the stage of the cancer.


The tumor and any organs or parts of organs that are affected by the tumor may be removed with surgery. The surgeon will remove the section of colon or rectum that contains the cancer and then sew the ends of the intestine back together. Lymph nodes around the tumor are removed with the bowel in order to remove cancer that may have already spread. It also allows the pathologist to determine the stage of the cancer accurately. This will allow your healthcare providers to determine if you need more treatment after you recover from surgery.


Another procedure, called a colostomy, is done when the cancer is so near the anus that there is not enough rectum left above the anus after surgery to allow the ends to be joined together. In this case, the surgeon makes an opening in the abdominal wall and attaches the healthy end of the shortened colon to the skin. After this procedure you will pass bowel movements through this opening and into a bag. You will be taught how to care for the colostomy. A colostomy can be temporary or permanent. You are much less likely to need a colostomy if the cancer is diagnosed in the earliest stages.


Other possible treatments in addition to surgery are:

  • chemotherapy, which uses anticancer drugs to kill cancer cells
  • biological therapy, which can help your immune system fight cancer or help lessen side effects from other cancer treatments
  • radiation therapy, which uses X-rays or other high-energy rays to kill cancer cells and shrink rectal tumors

How long will the effects last?

If it is detected early, colorectal cancer may be cured with surgery alone. In later stages, you may need additional treatment, such as chemotherapy and radiation therapy, to lower the risk of a return of the cancer. Your healthcare provider may ask you to see a medical oncologist after surgery to decide whether treatment with chemotherapy is needed.


Your chance of cure depends on how far the cancer has advanced. When a cancer is removed before it has spread into the wall of the colon, more than 90% of people survive 5 years or longer. The chance of survival decreases with advanced stages.


If you have a colostomy, your healthcare team will help you learn how to live with it. Most people lead healthy, active lives with colostomies. Your provider may suggest dietary changes that restrict gas-forming and odor-causing foods such as beans, eggs, fish, and carbonated drinks. In time, you will learn which foods you can cause problems for you.

How can I take care of myself?

Follow the treatment that you and your healthcare provider decide is best. Seek the advice of other health professionals as needed. Also, be sure to:

  • Get enough rest and sleep.
  • Eat healthy foods, following your after-surgery diet instructions.
  • Exercise according to your healthcare provider's recommendations.
  • Relax using techniques such as positive mental imaging, muscle relaxation exercises, and breathing exercises. Do fun activities to relieve stress.

Talk with a mental health professional about anxiety concerning cancer if you think it might help.


If you have a colostomy:

  • Learn how to take care of your colostomy.
  • Learn which foods you should not eat because they cause too much gas or make it hard for you to control your bowels.
  • Give yourself time to get used to the changes in your body. You may need to change how you dress to allow room for the colostomy and bag.
  • Seek sexual counseling for yourself and your partner if you feel you need it.
  • You may feel anger, frustration, grief, and embarrassment about the cancer and colostomy. Talk about your feelings. Let members of your care team know what you are thinking.

What can be done to help prevent colorectal cancer from occurring or recurring?


To prevent or detect recurrence of the cancer, follow the guidelines your healthcare provider gives you. Also, you should:

  • Keep all of your follow-up appointments with your provider.
  • Have routine colonoscopies to check for polyps according to your provider's recommendations.
  • Check yourself for symptoms or signs.
  • Call your provider if changes occur.

If you do not have colorectal cancer but are 50 to 75 years old and have an average risk of colorectal cancer, you should be screened with 1 of these 3 methods:

  • Have your stool checked for blood with a fecal occult blood test once a year.
  • Have a sigmoidoscopy exam every 5 years with fecal occult blood testing between these 5-year exams.
  • Have a colonoscopy every 10 years.

If you have a higher than normal risk for colorectal cancer, ask your healthcare provider when and how often you should be tested for colorectal cancer. You may need to start testing before you are 50.


For more information on cancer, contact national and local organizations such as:


Disclaimer: This content is reviewed periodically and is subject to change as new health information becomes available. The information provided is intended to be informative and educational and is not a replacement for professional medical evaluation, advice, diagnosis or treatment by a healthcare professional.


HIA File canc3521.htm Release 13/2010

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