Average risk men and women and their doctors can estimate the probability of that individual developing colon or rectal cancer by using an interactive tool available online. Developed by National Cancer Institute, the model is based on population research and cancer incidence information.
In developing the prediction tool, researchers matched 1,600 men and women with colon cancer and 650 with rectal cancer to nearly 1,900 similar individuals without cancer. Using identified risk factors for colorectal cancer, they were able to estimate the probability than an individual would develop colon or rectal cancer within the next 5, 10, or 20 years. The prospective National Institute of Health-American Association of Retired Persons diet and health study was used to validate the tool.
The risk calculator can predict the chance of developing colon cancer in the right or left side and of the colon as well as rectal cancer.
Its use is limited to white, non-Hispanic adults between the ages of 50 and 85. It should not be used in to calculate risk for people with ulcerative colitis, Crohn’s disease, familial adenomatous polyposis (FAP), or Lynch syndrome (also known as hereditary non-polyposis colon cancer or HNPCC). It is not appropriate for people who have already had colorectal cancer.
For average risk white men and women over the age of 50, risk is predicted by looking at:
- whether they have had a sigmoidoscopy or colonoscopy in the past 10 years
- whether they had a polyp diagnosed in the past 10 years
- height and weight to determine body mass index (BMI)
- their use of NSAIDS like aspirin, naproxen, ibuprofen, or Celebrex
- how many weekly servings of vegetables or leafy green salads they eat
- number of months of moderate physical activity over the past year and number of hours days each week they exercised moderately
- number of months of vigorous physical exercise in the past year and number of hours each week of vigorous exercise
- number of family members with colorectal cancer: none, one, two or more
For men, the questionnaire also includes smoking history. For women, menstrual cycles or hormone replacement therapy within the past two years is also a factor in determining risk.
In addition to the online tool, the assessment can also be completed using paper and pencil in about five to eight minutes.
While the tool can help estimate the possibility that an individual might develop colon or rectal cancer over the next five or ten years, it cannot absolutely say that any person will or will not get cancer. Explaining the tool, the NCI points out,
While risk may be accurately estimated for non-Hispanic white men and women ages 50 to 85, these predictions do not allow one to say precisely which people will develop colorectal cancer. The tool is designed to help patients and their healthcare providers make informed choices about when and how screening should take place.
The tool can help patients discuss their risk factors for colon or rectal cancer with their doctors, plan screenings, and consider changes to their lifestyles. It can also be used for research into chemopreventive agents or screening programs that might prevent colorectal cancer.
SOURCES: Freedman et al., Journal of Clinical Oncology, Early Release, published online December 29, 2008.
Park et. al, Journal of Clinical Oncology, Early Release, published online December 29, 2008.
Find the Colorectal Cancer Risk Assessment Assessment Tool on the National Cancer Institute website.
What This Means for Patients
While the Colorectal Cancer Risk Assessment Tool can give you and your doctor an accurate idea about how likely you are to develop colorectal cancer, it cannot tell you whether you will or will not get colon or rectal cancer.
The Colorectal Cancer Risk Assessment Tool was designed for use by health professionals and their patients. You should discuss the results and your personal risk of colorectal cancer with your healthcare provider.
You should continue getting regular colorectal cancer screenings. The strongest predictor of whether or not an individual would be diagnosed with colorectal cancer in the Assessment Tool was whether or not they had had a sigmoidoscopy or colonoscopy in the past ten years. Not having one increased risk of colon cancer for men almost threefold. Men had nearly four times the risk for rectal cancer without sigmoidoscopy or colonoscopy. Risk for women was slightly less, but they still had three times the risk for rectal cancer and over twice the risk for colon cancer without endoscopy screening.
Eating vegetables, exercising regularly, and maintaining a healthy weight all reduced risk. Discuss these with your doctor.