CARE model estimates risk in black women

December 1, 2007

A new model for calculating invasive breast cancer risk, called the CARE model, has been found to give better estimates of the number of breast cancers that would develop in African-American women age 50 to 79 years than an earlier model known as BCRAT (Breast Cancer Risk Assessment Tool), which was based primarily on data from white women

A new model for calculating invasive breast cancer risk, called the CARE model, has been found to give better estimates of the number of breast cancers that would develop in African-American women age 50 to 79 years than an earlier model known as BCRAT (Breast Cancer Risk Assessment Tool), which was based primarily on data from white women (Gail MH et al: J Natl Cancer Inst 99:1782-1792, 2007).

Because of the higher accuracy of the CARE model for African-American women, the authors are now recommending its use for counseling these women regarding their risk of breast cancer. It will be incorporated into the BCRAT on the NCI website by the spring of 2008.

The NCI investigators worked with colleagues from the Women's Contraceptive and Reproductive Experiences (CARE) Study, the Women' Health Initiative (WHI), and the Study of Tamoxifen and Raloxifene (STAR) to produce and test the new model.

The researchers examined data from 1,607 African-American women with invasive breast cancer and 1,637 African-American women of similar ages who did not have breast cancer. The factors used in the model were:

• Age at first menstrual period.

• Number of first-degree relatives (mothers and sisters) who had breast cancer.

• Number of previous benign breast biopsy examinations.

A woman's age at the birth of her first child, a risk factor for white women, did not improve prediction in African-American women and so was not included in the model.

Risk was calculated by combining information on these factors with African-American rates of new invasive breast cancer from NCI's SEER program and with national mortality data.

To test the model's accuracy, the investigators compared data in the CARE model with data from the 14,059 African-American women aged 50 to 79 in the WHI study who had no prior history of breast cancer. The model predicted that 323 women would be expected to develop invasive breast cancer, close to the 350 breast cancers in African-American women that actually occurred during the WHI follow-up.

"The CARE model predicted the numbers of breast cancer diagnoses well overall, and in most categories," said NCI's Mitchell H. Gail, MD, lead author.

To assess what the impact of using the CARE model might have been on the recently completed STAR prevention trial, the researchers used eligibility screening data from 20,278 African-American women who were examined in the trial between 1999 and 2004. They estimated that 30.3% of African-American women would have had significant 5-year invasive breast cancer risks based on the CARE mode vs 14.5% based on BCRAT.