Definition

Colorectal cancer is a disease in which cancer cells grow in the colon and/or rectum. The colon and the rectum are parts of the large intestine.

Cancer occurs when cells in the body divide out of control or order. If cells keep dividing, a mass of tissue, called a growth or tumor, forms. The term cancer refers to malignant tumors. They can invade nearby tissue and spread to other parts of the body. A benign tumor does not invade or spread.

Colon Cancer

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Causes

The cause of colorectal cancer is unknown.

Risk Factors

Research shows that certain risk factors are associated with the disease, these include:

Symptoms

Colorectal cancer often does not have any symptoms, but some symptoms associated with colorectal cancer include:

  • A change in bowel habits such as diarrhea , constipation , or feeling that the bowel does not empty completely—lasting for more than a few days in people aged 50 and older
  • Blood (either bright red or very dark) in the stool
  • Stools that are narrower than usual
  • Abdominal discomfort (frequent gas pains, bloating, fullness, and/or cramps)
  • Unexplained weight loss
  • Constant fatigue

These may also be caused by other, less serious health conditions. Anyone experiencing these symptoms should see a doctor.

Diagnosis

The doctor will ask about your symptoms and medical history. A physical exam will be done.

Tests include:

  • Digital rectal exam—use of a doctor's gloved finger to examine the rectum for lumps or growths
  • Fecal occult blood test —a test to check for hidden blood in the stool
  • Barium enema —a rectal injection of barium given to coat the lining of the colon and rectum; done before x-rays, in order to create better image of the lower intestine
  • Sigmoidoscopy —an examination of the lower colon using a lighted tube called a sigmoidoscope
  • Colonoscopy —examination of the rectum and entire colon using a lighted tube .called a colonoscope
  • Polypectomy —the removal of a polyp during a sigmoidoscopy or colonoscopy
  • Biopsy —the removal of colon or rectal tissue to be tested for cancer cells
  • CT scan —a type of x-ray that uses a computer to make pictures of structures inside the body; to identify the spread of the tumor outside the colon
  • MRI scan —a test that uses magnetic waves to make pictures of structures inside the body
  • Positron emission tomography (PET) —a test that produces images showing the amount of functional activity in tissue being studied

Treatment

Once colon cancer is found, staging tests are performed to find out if the cancer has spread and, if so, to what extent. Treatment depends on the stage of the cancer.

Treatments include:

Surgery

Surgery is the main treatment. It requires removal of the cancerous tumor and nearby colon or rectum tissue. It may also involve nearby lymph nodes.

Colectomy

In most cases, the healthy portions of the colon or rectum are reconnected. Sometimes they cannot be joined. In this case, a temporary or permanent colostomy is necessary. This is a surgical opening through the abdomen into the colon. Body waste can exit here into a special bag.

Radiation Therapy

This is the use of radiation to kill cancer cells and shrink tumors. It is directed at the site of the tumor from a source outside the body. It is used alone or in combination with chemotherapy in rectal cancer.

Chemotherapy

This therapy uses drugs to kill cancer cells. It may be given in many forms, including pill, injection, and via a catheter. The drugs enter the bloodstream and travel through the body killing mostly cancer cells. It can also kill some healthy cells.

If you are diagnosed with colorectal cancer, follow your doctor's instructions .

Prevention

The cause of most colorectal cancer is not known. However, it is possible to prevent many colon cancers by finding and removing polyps that could become cancerous. Beginning at age 50, both men and women at average risk for the development of colorectal cancer should follow one of the five screening options listed below:

  • Yearly fecal occult blood test or fecal immunochemical test
  • Flexible sigmoidoscopy every 3-5 years
  • Yearly fecal occult blood test or fecal immunochemical test plus flexible sigmoidoscopy every 5 years
  • Double contrast barium enema (x-rays of the colon and rectum) every 5 years
  • Colonoscopy every 10 years

Be sure to discuss these cancer screening tools with your doctor to see which option is best for you.

People with any of the following risk factors should begin colorectal cancer screening earlier at age 40 and/or undergo screening more often:

  • Strong family history of colorectal cancer or polyps
  • Known family history of hereditary colorectal cancer syndromes
  • Personal history of colorectal cancer or adenomatous polyps
  • Personal history of chronic inflammatory bowel disease