To test the accuracy of the model, researchers compared data in the CARE model with data from the 14,059 African American women aged 50-79 in the Women's Health Initiative (WHI) study who had no prior history of breast cancer. From the risk factor profiles for breast cancer that were collected at entry into the WHI, the researchers used the CARE model to estimate the number of women who would be expected to develop invasive breast cancer and found that the model predicted that 323 would be affected, close to the 350 breast cancers in African American women that actually occurred during the WHI follow up. According to Mitchell H. Gail, M.D., NCI, the lead author of this study, "The CARE model predicted the numbers of breast cancer diagnoses well overall, and in most categories."

One of the key uses of the BCRAT has been to determine eligibility criteria for a number of breast cancer prevention trials. For African American women 45 and older, the CARE model risk projections were usually higher than those from the BCRAT. To assess what the impact of using the CARE model might have been on a recently completed prevention trial, the researchers used eligibility screening data from 20,278 African American women who were examined in the Study of Tamoxifen and Raloxifene (STAR) trial between 1999 and 2004. The investigators estimated that 30.3 percent of African American women would have had significant five-year invasive breast cancer risks based on the CARE model, compared to only 14.5 percent based on BCRAT.


"African American women were both more interested in and more likely to enroll in the STAR trial compared to the earlier Breast Cancer Prevention Trial, but the recruitment process and our enrollment task would have been easier if the CARE model had been available," said Worta McCaskill-Stevens, M.D., NCI, one of the leaders of the STAR trial.

Additionally, inaccurate projections using the BCRAT could result in African American women receiving an underestimate of their breast cancer risk. As a result of this underestimate, African American women might not get counseling about actions they could take to reduce their risk. "There has been great interest in developing race- or ethnicity-specific adaptations of the BCRAT model that are based on sufficient race- or ethnicity-specific data, and the CARE data enabled us to develop the new model," said Gail.

It should be noted that the CARE model, like the BCRAT, needs to be approached with caution or avoided for certain special populations. These models should not be used for women with a previous history of breast cancer. The models tens to underestimate risk in women who have received radiation to the chest and in women who are known to carry mutations associated with increased risk of breast cancer, such as mutations in the BRCA1 and BRCA2 genes. While the CARE model has not yet been incorporated into the BCRAT on the NCI Web site, NCI plans to have the tool updated by the spring of 2008.

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