Colon and Rectal (Colorectal) Cancer

What is colorectal cancer?

Colorectal cancer is malignant cells found in the colon or rectum. The colon and the rectum are part of the large intestine, which is part of the digestive system. Because colon cancer and rectal cancers have many features in common, they are sometimes referred to together as colorectal cancer. Cancerous tumors found in the colon or rectum also may spread to other parts of the body.

Colorectal cancer is the third leading cause of cancer deaths in the United States. However, the number of new cases of colorectal cancer and the number of deaths due to colorectal cancer has decreased, which is attributed to increased sigmoidoscopic screening and polyp removal.

What are the symptoms of colorectal cancer?

The following are the most common symptoms for colorectal cancer, however, each individual may experience symptoms differently.

Beginning at age 50, both men and women should follow one of the examination schedules below:

• fecal occult blood test (FOBT) every year
• flexible sigmoidoscopy (FSIG) every five years
• annual FOBT and FSIG every five years
• double-contrast barium enema every five years
• colonoscopy every 10 years

People with any of the following colorectal cancer risk factors should begin screening procedures at an earlier age and be screened more often:

• strong family history of colorectal cancer or adenomatous polyps in a first-degree relative, in a parent or sibling before the age of 60 or in two first-degree relatives of any age
• family with hereditary colorectal cancer syndromes, such as familial adenomatous polyposis (FAP) and hereditary nonpolyposis colon cancer (HNPCC)
• >personal history of colorectal cancer or adenomatous polyps
• personal history of chronic inflammatory bowel disease

The symptoms of colorectal cancer may resemble other conditions, such as infections, hemorrhoids, and inflammatory bowel disease. It is important to talk to the physician since finding colorectal cancer early makes successful treatment more likely.

It is also possible to have colon cancer and not have any symptoms.

Anatomy of the colon:

The colon is the first six feet of the large intestine. It has four sections:

• The first section is called the ascending colon. It extends upward on the right side of the abdomen.
• The second section is called the transverse colon since it goes across the body to the left side.
• There it joins the third section, the descending colon, which continues downward on the left side.
• The fourth section is known as the sigmoid colon because of its S-shape.

The sigmoid colon joins the rectum, which in turn joins the anus, or the opening where waste matter passes out of the body.

What are the risk factors for colorectal cancer?

Risk factors may include:

• age
  Most people who have colorectal cancer are over age 50, however, it can occur at any age.
• personal history
  People who have had colorectal cancer, as well as ovarian,uterine, or breast cancers, have a slightly increased risk for colorectal cancer.
• family history
  People with first-degree relatives who have had colorectal cancer have an increased risk for colorectal cancer.
• diet
  Colorectal cancer is associated with a diet high in fat and calories, and low in fiber.
• ulcerative colitis
  People who have ulcerative colitis, inflamed lining of thecolon, have an increased risk for colorectal cancer.
• polyps
  Benign growths on the wall of the colon or rectum are common in people over age 50, and are believed to lead to colorectal cancer.

What is a risk factor?

A risk factor is anything that may increase a person’s chance of developing a disease. It may be an activity, such as smoking, diet, family history, or many other things. Different diseases, including cancers, have different risk factors.

Although these factors can increase a person’s risk, they do not necessarily cause the disease. Some people with one or more risk factors never develop the disease, while others develop disease and have no known risk factors.

But, knowing your risk factors to any disease can help to guide you into the appropriate actions, including changing behaviors and being clinically monitored for the disease.

What causes colorectal cancer?

The exact cause of most colorectal cancer is unknown, but the known risk factors listed above are the most likely causes. Less than 10 percent of colorectal cancers are caused by inherited gene mutations.

People with a family history of colorectal cancer, may wish to consider genetic testing. The American Cancer Society suggests that anyone undergoing such tests have access to a physician or geneticist qualified to explain the significance of these test results.

Prevention of colorectal cancer:

Although the exact cause of colorectal cancer is not known, it is possible to prevent many colon cancers through:

• diet and exercise
  It is important to manage the risk factors you can control, such as diet and exercise. Eating more fruits, vegetables, and whole grain foods and avoiding high-fat, low-fiber foods, plus appropriate exercise, even small amounts on a regular basis, can be helpful.
• drug therapy
  Some studies have shown that low doses of nonsteroidal anti-inflammatory drugs (NSAIDs) such as aspirin, and estrogen replacement therapy for post-menopausal women may reduce the risk of colorectal cancer. Discuss this with your physician.
• screenings
  Perhaps most important to the prevention of colorectal cancer is having screening tests at appropriate ages. Because some colorectal cancers cannot be prevented, finding them early is the best way to improve the chance of a successful treatment, and reduce the number of deaths caused by colorectal cancer.
  The following screening guidelines can lower the number of cases of the disease and can also lower the death rate from colorectal cancer by detecting the disease at an earlier, more treatable stage.

Methods of screening for colorectal cancer:

Screening methods for colorectal cancer, for people who do not have any symptoms or strong risk factors, include:

• fecal occult blood test
  a sample of stool is examined for blood. A test kit will explain how to take a sample at home. It is then returned to the physician's office to be checked.

One of the following:

• sigmoidoscopy
  a slender, flexible, hollow, lighted tube is placed into the rectum allowing the physician to look at the inside of it and part of the colon for cancer or for polyps.
• colonoscopy
  a long, flexible, lighted tube (much longer than a sigmoidoscope) about the thickness of a finger is inserted through the rectum up into the colon, allowing the physician to see the colon lining.
• barium enema with air contrast (also called a double contrast barium enema)
  barium sulfate, a chalky substance used to partially fill and open up the colon, is given in the anus and x-rays are made.

Diagnostic procedures for colorectal cancer:

In addition to a complete medical history and physical examination, diagnostic procedures for colorectal cancer may include:

• fecal occult blood test
• sigmoidoscopy
• colonoscopy
• barium enema
• biopsy
• CEA assay to measure a protein called carcinoembryonic antigen, which is sometimes higher in patients who have colorectal cancer.

Treatment for colorectal cancer:

Specific treatment will be determined by your physician(s) based on:

• your age, overall health, and medical history
• extent of the disease
• your tolerance for specific medications, procedures, or therapies
• expectations for the course of the disease
• your opinion or preference

Treatment choices for the person with colon cancer depend on the stage of the tumor if it has spread and how far. When the disease has been found and staged, your physician will suggest a treatment plan. Treatments may include:

• colon surgery
  The main treatment for colon cancer and the usual operation is called a segmental resection, in which the cancer and a length of normal tissue on either side of the cancer are removed, as well as the nearby lymph nodes.
• radiation therapy
  Radiation therapy is the use of high energy radiation to kill cancer cells either after surgery, to kill small areas of cancer that may not be seen during surgery, or instead of surgery. Radiation may also be used to ease (palliate) symptoms such as pain, bleeding, or blockage. There are two ways to deliver radiation therapy:
  • External beam radiation
    uses radiation from outside the body, which is focused on the cancer.
  • Internal radiation therapy
    uses small pellets of radioactive material placed directly into the cancer.
• chemotherapy
  Drugs (medications) are given into a vein or by mouth to kill cancer cells throughout the body. Studies have shown that chemotherapy after surgery can increase the survival rate for patients with some stages of colon cancer. Chemotherapy can also help relieve symptoms of advanced cancer.