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About Colorectal Cancer

The colon, also called the large intestine, runs from the cecum at the end of the small intestine to the anus. It’s about six feet in length. The last five to 10 inches of the colon is referred to as the rectum. The main function of the colon is to absorb water and some nutrients from food that has been broken down through the digestive system. The remnants become stool and stay in the colon until passed through the rectum.

Colorectal cancer — also sometimes called colon cancer — can occur anywhere in that six or so feet of large intestine and rectum. More than 140,000 new cases of colorectal cancer are diagnosed in the United States each year. Due to a lack of adequate screening, colorectal cancer is the third-leading cause of cancer-related death in the U.S., claiming more than 50,000 lives each year. According to the American Cancer Society, if everyone who should receive a colonoscopy went forward with the screening, the death rate from colorectal cancer could be reduced by 60 percent.

Most instances of colorectal cancer occur in adults age 50 and older — which is why basic screening guidelines dictate that adults should begin receiving regular colonoscopies beginning at age 50. It can, however, occur in people younger than 50; those who have a family history of colorectal cancer should consider being screened beginning before 50. The advocacy group Fight Colorectal Cancer estimates that as many as 1 in 3 adults age 50 and older are not being screened for colorectal cancer.

Colonoscopy is considered the best, most thorough screening for colorectal cancer. Not only can colonoscopy allow a gastroenterology specialist to find cancer at its earliest stages when treatment is most effective, it can allow the specialist to remove the polyps in the colon that lead to cancer and actually prevent the cancer from occurring. Many people put off receiving a colonoscopy because they worry it will be uncomfortable — especially preparing for the procedure — though colonoscopy prep is generally much easier now than it has been in the past.


Generally speaking, any change in your regular bowel habits should be discussed with your healthcare provider. Specific symptoms of colorectal cancer can include:

  • A change in bowel habits that lasts for more than a few days, such as diarrhea, constipation or a feeling that your bowel is not empty after a bowel movement
  • Bright red or very dark blood in your stool
  • Constant fatigue
  • Stools that are thinner than usual
  • Stools that look slimy or have mucous on them
  • Ongoing gas pains, bloating, fullness or cramps
  • Unexplained weight loss
  • Vomiting

However, one reason colorectal cancer is so dangerous is because it can occur with no symptoms at all — which makes screening that much more important.

Risk Factors

There are certain risk factors that can increase the likelihood of developing colon cancer, including:

  • Being African American
  • Having a history of smoking and tobacco use
  • Having a family member who had colorectal cancer or colon polyps
  • Living with an inflammatory bowel disease, such as ulcerative colitis or Crohn’s disease
  • Experiencing a change in bowel movements, blood in your stool or abdominal pain

While these can increase your risk for colon cancer, the disease can still affect people who have none of these factors. You can find a complete list of risk factors in Tanner’s Health Library. You can also learn more about ways you can reduce your risk for colorectal cancer in Tanner’s blog, TheScope.org.

The Health Library also includes a colorectal cancer risk assessment that asks just 11 questions to calculate your risk for developing colorectal cancer.

Additional Resources

These resources can help you learn more about colorectal cancer:

  • The Digestive System: An Overview (Tanner Health Library)
    What is the small intestine, large intestine and esophagus? How does your body digest food? What are the components of the human digestive system? This article from Tanner’s Health Library offers a wealth of explanation.
  • Colorectal Cancer: Introduction (Tanner Health Library)
    An overview of what cancer is, the types of cancer that can occur in the colon and rectum, and how colorectal cancer begins, grows and spreads.
  • Colorectal Cancer: Just the Facts (TheScope.org)
    This blog, from board-certified gastroenterology specialist Prashant Sharma, MD, provides statistics and information on the condition.
  • Colorectal Cancer: Diagnosis (Tanner Health Library)
    How does your doctor determine if you have colorectal cancer? This article in Tanner’s Health Library offers information on the process of diagnosing colorectal cancer, including biopsy.
  • A Guide to Colorectal Cancer Screening (TheScope.org)
    The best way to defend yourself against colorectal cancer — one of the world’s deadliest forms of cancer for both men and women — is screening. Thelma Wiley Lucas, MD, a board-certified gastroenterologist, offers advice in this blog post from TheScope.org.
  • Colorectal Cancer Topics (Tanner Health Library)
    Peruse a host of articles on colorectal cancer treatments, prognosis, managing side effects and more.
  • A Dancer and a Warrior (SurgeryAtTanner.org)
    Diagnosed with colorectal cancer? Take heart — many people successfully undergo treatment and return to the things they love. Gerald Harjo, a 48-time national championship Native American dancer, shares his story.
  • A Young Patient, An Advanced Surgery (SurgeryAtTanner.org)
    Constance Buchanan didn’t expect to face colorectal cancer in her early 30s, but the hard-working mother of two from Carrollton overcame the cancer with the help of her patient care team at Tanner. She and her surgeon also shared the story with news station Fox 5 Atlanta.
  • Tiny Incisions, Bright Futures (SurgeryAtTanner.org)
    Marie Dobbs was 49 when she learned she had colorectal cancer. But she worked with her patient care team at Tanner Cancer Care to overcome the disease.

Call 770.214.CARE now for a referral to a gastroenterology specialist.

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