Colorectal cancer predicted risk online (CRC-PRO) calculator using data from the multi-ethnic cohort study

Abstract

Background: Better risk predictions for colorectal cancer (CRC) could improve prevention strategies by allowing clinicians to more accurately identify high-risk individuals. The National Cancer Institute's CRC risk calculator was created by Freedman et al using case control data.

Methods: An online risk calculator was created using data from the Multi-Ethnic Cohort Study, which followed >180,000 patients for the development of CRC for up to 11.5 years through linkage with cancer registries. Forward stepwise regression tuned to the c statistic was used to select the most important variables for use in separate Cox survival models for men and women. Model accuracy was assessed using 10-fold cross-validation.

Results: Patients in the cohort experienced 2762 incident cases of CRC. The final model for men contained 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 final model for women included 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 calculator demonstrated good accuracy with a cross-validated c statistic of 0.681 in men and 0.679 in women, and it seems to be well calibrated graphically. An electronic version of the calculator is available at http://rcalc.ccf.org.

Conclusion: This calculator seems to be accurate, is user friendly, and has been internally validated in a diverse population.

Keywords: Colorectal Cancer; Medical Decision Making; Prevention and Control; Risk.

Figure 1A

Nomogram for predicting colorectal cancer risk in men. Instructions: Draw a perpendicular line from the patient's age to the “points” axis and record the value. Repeat this process for the remaining variables and tally. The 10-year risk of colorectal cancer (CRC) is identified where a line drawn straight down from the “total points” axis intersects the “10-year risk of CRC (%).” Please note that the “years of education” variable has a U-shaped relationship with the 10-year risk of CRC. That is, the lowest risk of CRC occurs at 8 years and increases as you move along the top of the axis from left to right until reaching the highest risk at 14 years, and then it decreases along the bottom of the axis as you move to the left from 14 to 16 years.

Figure 1B

Nomogram for predicting colorectal cancer risk in women. NSAIDS, nonsteroidal anti-inflammatory drugs.

Figure 2

Calibration curve for the prediction in men (A) and women (B). The calibration curves were created by plotting the mean predicted risk of colorectal cancer in each quintile of risk on the x-axis against the corresponding Kaplan-Meier (K-M) estimated incidence in the same quintile. Error bars reflect the 95% confidence interval around the K-M estimate. The risks are displayed as probabilities. Perfect calibration would fall directly on the 45-degree line.