Colorectal Cancer

Colorectal Cancer

What is colorectal cancer?
Colorectal cancer is a cancer that develops anywhere in the large intestine.  The majority of colorectal cancers begin as benign polyps inside the colon or rectum.

Colorectal cancer is the second-leading cause of cancer death in the U.S. when men and women are combined, but it can often be prevented or detected early through a screening colonoscopy.

What causes colorectal cancer?
The exact cause of most colorectal cancers is unknown.  Colon cancer develops due to changes in the colon lining.  These changes may be inherited or develop as the result of mutations occurring during a person’s life, the causes of which are not fully understood. Common risk factors are family history of colorectal polyps or colorectal cancer, personal history of  ulcerative colitis or Crohn’s disease, high fat diet, obesity or smoking.  However, some patients may have none of these risk factors, thus screening all individuals over age 45 years is important.

How does screening prevent colorectal cancer?
Screening can prevent colorectal cancer through the detection and removal of precancerous growths as well as detect cancer at an early stage, when treatment is usually less extensive and more successful.

Why is a polyp dangerous?  
When a polyp progresses to cancer, it can extend into the wall of the colon or rectum where it can invade blood or lymph vessels. Cancer cells typically spread first into nearby lymph nodes, which are crucial for helping our bodies fight infections. They can also be carried via blood vessels to other organs and tissues, such as the lungs, liver, lining the abdomen and other parts of the body. This spread of cancer to parts of the body far away from where the tumor started is called metastasis.

What are the symptoms of colorectal cancer?
It’s crucial to know the symptoms, however, early stages of colorectal cancer don’t usually cause symptoms so proactive screening is one of the only ways to detect these types of cancers.


  • Rectal bleeding
  • Change in bowel habits
  • Vague abdominal pain
  • Weakness and fatigue
  • Unintended weight loss
  • Change in caliber of stool

Risk factors:

  • Age (45+)
  • Family history
  • Gender (men are at greater risk)
  • History of IBD
  • Race (risk is higher for African Americans)
  • Lifestyle (smoking, obesity, lack of physical exercise, diet, poor nutrition)
  • Medical history (diabetes, Ulcerative Colitis, Crohn’s disease)

What are the tests used to diagnose colorectal cancer?
Your gastroenterologist will help determine which test is appropriate for you.  Test options include:

  • Colonoscopy – The doctor uses a thin, flexible, lighted tube to check for polyps or cancer inside the rectum and the entire colon. During the test, the doctor can find and remove most polyps and some cancers.
  • Flexible sigmoidoscopy – A short, thin, flexible, lighted tube is inserted the rectum to check for polyps or cancer in the bottom third of the colon and rectum.
  • High-sensitivity stool test for blood – This test is performed at home by using a stick to obtain a small amount of stool.  The stool samples are returned to your doctor to be tested for occult blood.  However, stool tests may miss precancerous polyps and cancers and are therefore not a substitute for colonoscopy screening.

What age should I start getting screened for colorectal cancer?
Guidelines from the United States Preventive Services Task Force state that all average-risk people aged 45 and above should begin screening for colorectal cancer. This change is due to the alarming increases in colorectal cancer among a younger demographic. By 2030, researchers predict that colorectal cancer will be the leading cause of cancer deaths in people ages 20-49.

Fortunately, screening for colorectal cancer in average-risk individuals is credited as the largest single factor for decreasing rates of colorectal cancer.

How can I prevent colorectal cancer?
If you’re at average risk, start talking to your gastroenterologist at age 45 about screening options. If you’re at high risk, you may need to get screened sooner. 

Remember, 90 percent of all colorectal cancer cases and deaths are preventable by removing polyps and cancer can be successfully treated — and often cured — when detected early.