Colon Cancer Signs and Symptoms: What You Need to Know

August 31, 2020

Medically Reviewed By: Jeffrey A. Meyerhardt, MD, MPH

Colon cancer is the fourth most common cancer diagnosed in men and women in the United States. Colon and rectal cancers are often collectively referred to as colorectal cancer.

Most colorectal cancers start as a growth on the inner lining of the colon or rectum. These growths — known as polyps — can turn into cancer, but there are also polyps that don’t become cancerous.

There has recently been a rise in colon cancer in younger adults for reasons that are not completely clear yet. However, this highlights the importance of notifying your physician if you have any concerning symptoms or other bowel concerns.

What are the symptoms of colon cancer?

Most patients diagnosed with colorectal cancer do not have symptoms, but there are some signs and symptoms to be aware of, which may include:

  • A change in bowel habits, such as diarrhea or constipation
  • Blood in the stool or dark stools
  • Abdominal bloating
  • Rectal bleeding
  • Cramping
  • Fatigue
  • Weight loss

These symptoms typically develop when the cancer has progressed, so it’s important to proactively screen for cancer early, before symptoms develop.

How do I know if I need to be screened for colon cancer?

Current guidelines suggest for patients to start screening at age 50, unless they have certain risk factors. Those would include having a family history — particularly, people who’ve had younger family members who were diagnosed with colon cancer — or, having a colon or rectal polyp, or having certain diseases like ulcerative colitis or Crohn’s disease.

The American Cancer Society recently came out with guidelines to suggest that screening should actually start at age 45; the risk is still very low in those under 50, but it is relatively increasing compared to where it was several decades ago.

Screening guidelines include checking stool for blood that can’t be seen, includes sigmoidoscopy, or, a full colonoscopy which looks at your entire colon. The most effective screening is a colonoscopy.

How can I lower my risk of colon cancer?

You can help lower your risk of developing colon cancer by maintaining a healthy weight, getting regular exercise, eating lots of fruits and vegetables, limiting alcohol intake and stopping — or never — smoking. If you notice any change in your bowel habits or are experiencing persistent digestive symptoms, it’s important to contact your doctor.

About the Medical Reviewer

Jeffrey A. Meyerhardt, MD, MPH

Dr. Meyerhardt received his MD from Yale School of Medicine in 1997. He completed a residency in internal medicine at Beth Israel Deaconness Medical Center, in Boston, followed by a medical oncology fellowship at DFCI. He joined the Gastrointestinal Cancer Center at DFCI in 2002..