First Signs of Colon Cancer

The colon makes up the major portion of the large intestine, which serves to complete the digestive process. Polyps, bits of swollen or overdeveloped membrane, sometimes grow inside the colon. Though initially benign, some polyps develop into colon cancer, which is the third most common type of cancer in the United States, according to the M.D 1. Anderson Cancer Center at the University of Texas 3.

Is This an Emergency?

If you are experiencing serious medical symptoms, seek emergency treatment immediately.

Few real symptoms of colon cancer appear in its early stages; many symptoms of the disease are fairly generalized and are, therefore, common to a variety of ailments 1. When symptoms do appear, says the Mayo Clinic, they likely will vary depending on the location and size of the cancer 1.

Change In Bowel Habits

The earliest sign of colon cancer for many people is a change in the frequency, quality or consistency of their bowel movements 1. This might include feeling like you don’t completely empty your bowel or feeling like you need to defecate when it’s unnecessary; frequent fullness, bloating or cramps; diarrhea or constipation; a difference in the shape of the stool, such as being more narrow than usual; and tarry stools or mucus in the stool.


Another, more compelling sign of colon cancer is bleeding from the rectum or blood in the stool, sometimes seen in the toilet following a bowel movement 1. While not a definitive indication of colon cancer, it’s a sure sign that you need to make an appointment with your doctor 1.

Other Possible Symptoms

While less diagnostic than the change in bowel habits or blood in the stool, some people do experience persistent fatigue, weakness and unexplained weight loss. While many different ailments present with these symptoms, the M.D. Anderson Cancer Center recommends you make an appointment with your physician if your symptoms last for more than two weeks.

Testing for the Unseen Early Symptoms

Because colon cancer can develop without noticeable signs, the American Academy of Family Physicians recommends regular screening for the disease starting at about age 50, younger if you are at higher risk, such as having Crohn’s disease or colitis, or a family history of colon cancer 14. Several screening tests are available, such as a fecal occult blood test, which can identify blood in the stool that might not be observable, and a colonoscopy, which can find and remove polyps before they become symptomatic, or worse, cancerous.