Each year, an estimated 102,480 colon and 40,340 rectal cancers are diagnosed in the United States.
What is Colorectal Cancer?
Colorectal cancer is a disease in which cancerous (malignant) cells form in the tissues of the colon or the rectum. Both the colon and rectum are part of the body's digestive or gastrointestinal (GI) system; colon and rectal cancers are grouped together because the colorectal family of cancers has many features in common.
Risk Factors and Symptoms
Risk factors of colorectal cancer may include:
- Family history.
- Personal history of cancer.
- History of polyps in the colon.
- History of ulcerative colitis (ulcers in the lining of the large intestine) or Crohn's disease.
- Certain hereditary conditions, such as familial adenomatous polyposis and hereditary nonpolyposis colon cancer (HNPCC; Lynch Syndrome).
What are symptoms of colorectal cancer?
Colorectal cancer symptoms and warning signs may include the following:
- Change in bowel habits.
- Blood (either bright red or very dark) in the stool.
Other conditions may also cause the same symptoms. Ask your doctor if you have any concerns.
You should consult a doctor if any of the following problems also occur:
- Diarrhea, constipation, or feeling that the bowel does not empty completely
- Stools that are narrower than usual
- Frequent gas pains, bloating, fullness, or cramps
- Weight loss for no known reason
- Feeling very tired
Diagnosing and Staging
Tests that examine the colon, rectum, rectal tissue, blood, and stool are used to detect and diagnose this kind of cancer.
The following tests and procedures may be used:
- Physical exam and history
- Fecal occult blood test
- Digital rectal exam
- Barium enema
A colorectal screening can detect cancer at an earlier stage when it may be more treatable.
It is recommended that adults over age 50 are screened regularly. Screenings may include any of the tests listed above.
Stages of Colorectal Cancer
After cancer has been diagnosed, surgery may be performed to find out if cancer cells have spread from within the colon or rectum to other parts of the body (metastasized). This process is called staging.
If, after surgery, it is determined that the disease has spread, the following tests may be performed to determine the stage of cancer:
- CT scan
- Endoscopic ultrasound (EUS)
- Magnetic resonance imaging (MRI) scan
- Positron emission tomography (PET) scan
It is important to know the stage in order to plan treatment.
Metastatic Colorectal Cancer
When cancer cells break away from the primary (original) tumor and travel through the lymph system or the blood system to other places in the body, another (secondary) tumor may form. This process is called metastasis.
The secondary (metastatic) tumor is the same type of cancer as the primary tumor.
For example, if the cells spread to the liver, the cancer cells in the liver are actually colorectal cancer cells. The disease is metastatic colorectal cancer, not liver cancer.
There are three ways colorectal cancer can spread in the body:
- Through tissue: cancer invades the surrounding normal tissue.
- Through the lymph system: cancer invades the lymph system and travels through the lymph vessels to other places in the body.
- Through the blood: cancer invades the veins and capillaries and travels through the blood to other places in the body.
More About Colorectal Cancer