New Study Evaluates Online Colorectal Cancer Risk Calculators

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Many individuals considering screening for colorectal cancer may want information on their personal risk when making decisions about screening—such as whether to select an at-home stool-based test or colonoscopy. Investigators evaluated five online colorectal cancer risk calculators to determine their availability, ease of use, risk-prediction capabilities, and “behind-the-curtain” qualities to demonstrate how each was developed and whether it was based on rigorous statistical evidence. These findings were published by Maratt and Imperiale in The American Journal of Medicine.

Analysis Details

To compare the risk calculators, the investigators reviewed published data on the tools—sometimes finding none—and created hypothetical test scenarios.

The investigators noted that all of the online risk calculators required individuals to input their age, sex, body mass index, tobacco use, and family history of colorectal cancer. Queries on race, ethnicity, education level, history of diabetes, history of colon polyps, dietary habits, medications, and physical activity were inconsistently included.

They found that there was a widely variable amount of evidence supporting the various risk assessment tools. However, for the short-term risk of colorectal cancer—5 years and, in some cases, 10 years—there was fairly close agreement among the risk calculators. There was less consistency in predicting lifetime risk.

Overall, the investigators found the National Institutes of Health’s National Cancer Institute (NCI) risk assessment tool to be the most credible online risk calculator for colorectal cancer.


“We conducted this study so that the public and clinicians will be aware that these risk-assessment tools are easily accessible and to provide guidance on how to decide which to use,” explained study author Jennifer K. Maratt, MD, MS, Assistant Professor of Medicine in the Division of Gastroenterology and Hepatology at the Indiana University School of Medicine and a research scientist at Regenstrief Institute. Dr. Maratt noted that because the NCI’s risk calculator was developed and validated in a U.S. patient population, it may be the best risk calculator available for individuals living in the United States (when compared with other risk calculators). “Also, a risk prediction tool such as the NCI risk calculator could potentially be linked to and integrated into a patient’s electronic health record, a feature that could enable clinicians to consider many factors beyond age—such as family history [of colorectal cancer], tobacco use, diet, exercise, and other lifestyle habits, for example—that influence risk, when discussing colorectal cancer screening with patients,” she highlighted.

“We were surprised to learn that some risk calculators had no evidence but [were] pleased to learn that the NCI’s risk assessment tool for colorectal cancer has been validated. We were not surprised that long-term risk was more difficult for the calculators to estimate because people’s behaviors can change over time,” stressed study author Thomas F. Imperiale, MD, the Lawrence Lumeng Professor of Gastroenterology and Hepatology as well as Professor of Medicine in the Division of Hematology/Oncology at the Indiana University School of Medicine, Medical Director at Margaret Mary Health, and a research scientist at Regenstrief Institute. “Patients can choose to continue with certain lifestyle choices, discontinue some, or take on new ones—and of course, they can choose to get screened or, unfortunately, choose not to be screened,” he concluded.

The NCI’s colorectal cancer online risk assessment tool can be found at

Disclosure: For full disclosures of the study authors, visit

The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.