New Online Individual Risk Calculator for Colorectal Cancer

Researchers say their new risk calculator can estimate an individual’s risk of developing colorectal cancer.

Researchers at the Cleveland Clinic and Case Western Reserve University in Cleveland have developed a new online colorectal cancer (CRC) risk assessment tool, which the authors say can accurately estimate an individual’s risk of developing CRC.

The new calculator is called Colorectal Cancer Predicted Risk Online (CRC-PRO) and is available here. It is designed to facilitate the decision-making process of if and when to screen for colorectal cancer for the patient and physician. The article describing the new tool was published in the Journal of the American Board of Family Medicine.

“There are risk tools for heart disease and other conditions, but risk estimates for colon cancer are mainly confined to fairly general measures, such as age and family history,” said Douglas Corley, MD, PhD, a gastroenterologist and cancer researcher at Kaiser Permanente Northern California Division of Research. “This calculator provides a more accurate estimate of individual risk.”

Predicting a patient’s risk for CRC and screening higher-risk individuals is a way to potentially prevent diagnosis of CRC at a late stage, as well as death from colorectal cancer. Physicians generally use family history, age, and any prior history of precancerous polyps to guide screening initiation and screening frequency.

Both the National Cancer Institute and the American Cancer Society recently reported that both deaths from colorectal cancer and incidence rates are declining for both men and women. These trends are at least partly attributed to screening.

Currently guidelines recommend that individuals, age 50 or older, undergo screening every 5 years.

“The availability of individual level risk calculators will better allow physicians and patients to evaluate their risk, but what to do with this assessment also depends upon other factors, such as overall health and life expectancy [of the patient], to determine whether there is a benefit of screening, particularly when using more invasive tests such as colonoscopy,” added Corley.

“It is hoped that the calculator created in this study can help to improve the assessment of CRC risk in individual patients and can encourage the use of absolute risk thresholds for decision-making,” said the study authors.

This new tool, the authors said, could parse patients into those who have a true risk of developing CRC and those who do not, honing in on the patients who really need to be screened for this cancer type.

Brian Wells, MD, PhD, of the department of quantitative health sciences at the Cleveland Clinic, and colleagues, analyzed data from 180,630 individuals, age 45 or older, from the Multiethnic Cohort Study conducted by the University of Hawaii to create the online risk calculator. The study had followed patients for up to 11.5 years through cancer registry data, identifying factors linked to risk of developing CRC. Among the patients in the cohort, 2,762 were diagnosed with CRC.

The risk calculator for men includes age, ethnicity, pack-years of smoking, alcoholic drinks per day, body mass index, years of education, regular use of aspirin, family history of colon cancer, regular use of multivitamins, ounces of red meat intake per day, history of diabetes, and hours of moderate physical activity per day.

The risk calculator for women includes age, ethnicity, years of education, use of estrogen, history of diabetes, pack-years of smoking, family history of colon cancer, regular use of multivitamins, body mass index, regular use of nonsteroidal anti-inflammatory drugs, and alcoholic drinks per day.

The researchers found that beyond 11 or 12 different factors, there was little gain in accuracy if more variables were included.

Age was a major factor that contributed to the accuracy of the prediction calculator, providing evidence for the current age-based screening guidelines. Still, the authors found that other factors could cause risk to vary greatly. For example, the lowest 10-year risk for a 50-year-old woman based on CRC-PRO was 0.2%, while the highest risk for a 50-year-old woman was greater than 2%, a more than 10-fold difference in risk.

This risk calculator does not take into account inflammatory bowel disease (IBD), a known risk factor for CRC, because the cohort study used to create the risk calculator did not capture this patient information. “In practice, patients with IBD should undergo more aggressive screening and prevention strategies, as reflected in a separate set of guidelines that have been established for these patients,” said the study authors.

Those with a risk of less than 1% may be able to delay or opt out of CRC screening, particularly women who are at lower risk, said the authors, noting other studies that have shown the cost-effectiveness of a single screening during a lifetime for very low-risk patients.

“The user-friendly CRC risk calculator created in this project seems to have good prediction accuracy and to be well calibrated in the 10-fold cross-validation,” concluded the authors. Further studies to assess the cost-effectiveness of screening using this new tool could further illuminate its value.