Employee & Community Health

Answering your colon cancer questions

3/12/2018 by G. A. (Sam) Radke, PA-C


Q: What is colon cancer?

A: Colon cancer is cancer of the large intestine. Rectal cancer is cancer of the last several inches of the colon. Together, they're often referred to as colorectal cancers. 

Q: Who gets colon cancer? 

A: Although colorectal cancer can occur in people younger than 50, more than 90% of the cases are in those older than 50. The average age for colon cancer patients in the U.S. is 72; men have a slightly higher risk than women. 

Q: What causes colon cancer?

A: In most cases, it's not clear what causes colon cancer, although a small percent of cases are hereditary. 

ColonMedicalImageQ: How does colon cancer start?

A: Most colon cancers begin as small, noncancerous polyps. Over time, some of the polyps become cancerous.

Q: Are there signs and symptoms of colon cancer?

A: In some cases there are symptoms, but most of the time, there are none. Some signs and symptoms potentially linked to colon cancer include:

  • Change in your bowel habits or the consistency of your stool that lasts longer than four weeks. 
  • Rectal bleeding.
  • Persistent abdominal discomfort, such as cramps, gas or pain. 
  • A feeling that your bowel doesn't empty completely. 
  • Night sweats, unexplained weight loss, fatigue.

Q: What are some risk factors that may increase your chances of developing colon cancer?

A: The risk factors for colon cancer include: 

  • Older age
  • African-American
  • Personal history of colorectal cancer or polyps
  • Inflammatory intestinal conditions, such as ulcerative colitis and Crohn's disease
  • Inherited syndromes that increase colon cancer risk
  • Family history of colon cancer
  • Low-fiber, high-fat diet
  • Sedentary lifestyle
  • Diabetes
  • Obesity
  • Smoking
  • Alcohol
  • Radiation therapy for cancer that was directed at the abdomen to treat a previous cancer

Q: At what age should I start thinking about being tested for colon cancer?

A: The recommended age for a first colon screening, if you are at average risk for colon cancer, is 50. You should be seen earlier if you're at an increased risk, such as having a family history of colon cancer or polyps; African-Americans should be screened at age 45. 

Q: What tests are available for colon cancer screening?

A: There are various tests, but the most common one is colonoscopy. During a colonoscopy, a scope is inserted into the rectum and advanced through the entire colon to detect polyps or growths. Another test, which was introduced in 2016, is Cologuard. It's a non-invasive test for average-risk patients that can be taken at home. There's no prep, change in your diet or medication needed. 

Q: What is the outlook if you have colon cancer?

A: Many people who have had colorectal cancer live a normal life time. The most critical factors are the stage of the cancer, number of involved lymph glands, if it has spread, and the quality of surgery for rectal cancer. According to the National Cancer Institute, survival for Stage I colon or rectal cancer is about 93%. Survival for Stage II is between 72 and 85%, and for Stage III, 44 to 83%. Stage IV cancer has a poor prognosis; about 8% of patients are alive at five years. 

G. A. (Sam) Radke is a PA-C at Mayo Clinic Employee and Community Health's (ECH) Division of Primary Care Internal Medicine (PCIM). She has a particular interest in diabetes, hypertension, hyperlipidemia and women's health.