Dr. Rex answers questions about rising colorectal cancer rates among younger adults

Douglas Rex, M.D., an internationally recognized gastroenterologist, focuses his research on colorectal cancer screening and colonoscopy. Dr. Rex answered questions about a recent study from the American Cancer Society that found that colorectal cancer rates are increasing among younger adults.   

Traditionally, aging is a risk factor for most cancers and that has included colorectal cancer (cancer of the colon and rectum). The American College of Gastroenterology recommends a baseline colorectal screening at the age of 50 (age 45 for African Americans), with subsequent screenings every 10 years, provided no problems are discovered. Other than age, what are some of the other risk factors?

Dr. Rex: Colorectal cancer incidence began to decrease in persons over age 50 in 1985 and the decline accelerated to about 3% to 4% per year in 2000, coinciding with when Medicare approved screening colonoscopy. The reasons for the increase in persons under age 50 for the past decade are not clear. In general, risk factors for colorectal cancer include age, positive family history, cigarette smoking, diabetes, obesity and metabolic syndrome. It's possible that diabetes and obesity account for some of the rise but the reasons are still uncertain.

Human colon cancer cells with the cell nuclei stained red and the protein E-cadherin stained green.

--NCI Center for Cancer Research

Are these numbers alarming or a reflection of changing times and changing diets?

Dr. Rex: The underlying causes are unknown. While the risk is increasing, it's important to remember that the absolute risks in persons under age 50 are still much lower than in older people.

What are some of the early symptoms of colon cancer?

Dr. Rex: The later stage of onset may reflect delay in diagnosis in some instances. The symptom of greatest importance is rectal bleeding, which may take the form of blood in the toilet bowel or unexplained iron deficiency anemia  Other symptoms such as change in bowel habit and abdominal pain are of less importance provided they are not accompanied by bleeding.

If you are under the age of 50 and are concerned about your symptoms, what is the best course of action?

Dr. Rex: See your doctor and request an evaluation. Colonoscopy remains the best test.

Have detection methods improved and, if so, which method do you consider the best option for screening younger adults?

Dr. Rex: Each case should be considered individually. If a young person has rectal bleeding with an obvious source on perianal inspection, then anoscopy or flexible sigmoidsocopy, followed by treatment and follow-up in the office until the symptom resolves, may be adequate. If there is painless bleeding and no anal source evident on inspection and digital exam, colonoscopy is the best test.

What is colorectal cancer?

You can learn more about colorectal cancer from the National Cancer Institute.