Colonoscopy is the most definitive test for colorectal cancer because it allows doctors to examine the entire colon for cancerous growths and polyps (benign growths that may develop into cancer). But the question is: at what age do people need to begin having this invasive and relatively expensive test?
Each year, colorectal cancer occurs in 24 of every 100,000 people between the ages of 40 and 49. But in people ages 50 to 54, the rate jumps to 48 in every 100,000 people. For this reason, national colorectal cancer screening guidelines currently recommend colonoscopy for people age 50 and older at average risk for colorectal cancer. Those at higher risk are advised to have a colonoscopy earlier. However, 7% of colorectal cancers occur in people under age 50 and some research suggests these cancers are more aggressive.
Research recently published in
The New England Journal of Medicine
provides new evidence to support the recommendation of starting colonoscopy at—rather than before—age 50.
About the study
Researchers from Indiana University, the University of North Carolina, and Eli Lilly studied the results of colonoscopies in 906 men and women between the ages of 40 and 49. These people had participated in a free colonoscopy program provided by their employer, Eli Lilly, between September 1995 and April 2000.
To be eligible for the free colonoscopy, participants had to meet the following criteria: no history of colorectal cancer, colorectal polyps, or inflammatory bowel disease and no symptoms of colorectal cancer (rectal bleeding, recent change in bowel habits, and recent or current lower abdominal pain). This information was confirmed in a telephone interview with each participant before scheduling the colonoscopy.
For this recent analysis, the researchers reviewed the colonoscopy results to determine how many “advanced” growths were found in the 906 people who were screened. Advanced growths included:
Growths measuring 1 cm or more in diameter
Polyps with abnormal cell characteristics
No colorectal cancers were detected in the 906 people screened with colonoscopy. Advanced growths were detected in 3.5% of people and over half of these growths were in areas of the colon viewable with sigmoidoscopy (a less invasive procedure).
Although these results are interesting, there are limitations to this study. This analysis did not include information about personal risk factors for colorectal cancer (family history of the disease, race, and body mass index), so we don’t know if participants had any of these risk factors or not. In addition, the majority of participants were white and middle-to-upper-middle class, so it is unclear whether these results apply to people of other racial, ethnic, and socioeconomic groups. Finally, people who had symptoms of colorectal cancer or a history of colorectal cancer were not included in this screening program. For this reason, these results should not be applied to people at increased risk of colorectal cancer. More research is needed to determine optimal screening procedures for people at high risk.
How does this affect you?
Does this mean you won’t get colorectal cancer before age 50? Not necessarily. These results suggest that the current recommendation of colonoscopy for people age 50 and older is appropriate for people at average risk for colorectal cancer. But don’t forget that if you have risk factors for colorectal cancer, you need to be screened earlier and more often.
In addition, the researchers have no way of knowing if the advanced growths found in this study will progress to cancer. And it’s important to understand that the definition of “advanced growth” is somewhat arbitrary.
Finally, 7% of colorectal cancers occur in people under age 50 and some research indicates these cancers are more aggressive. So although this study adds evidence to support the recommendations that people under age 50 of average risk do not need to have a colonoscopy, people at increased risk for colorectal cancer may benefit from colonoscopy before age 50. You're considered to be at increased risk if you have:
Personal or family history of colorectal cancer or adenomatous polyps
Personal history of chronic inflammatory bowel disease, such as ulcerative colitis or Crohn's disease
Personal or family history of other types of cancer, such as those involving the breast, ovary, uterus, and other organs
Imperiale TF, et al. Results of screening colonoscopy among persons 40 to 49 years of age.
New England Journal of Medicine
. June 6, 2002;346(23):1781-1785.
Please be aware that this information is provided to supplement the care
provided by your physician. It is neither intended nor implied to be a
substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER
IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the
advice of your physician or other qualified health provider prior to
starting any new treatment or with any questions you may have regarding a