New Prediction Model May Provide More Accurate Assessment of Breast Cancer Risk in Hispanic Women
A prediction model created for projecting absolute invasive breast cancer risk in Hispanic women provides a more accurate assessment of their risk of developing breast cancer compared with existing models that are based on data from non-Hispanic women, according to a new study by Banegas et al. Currently, the Breast Cancer Risk Assessment Tool (BCRAT) from the National Cancer Institute (NCI) is widely used to estimate the absolute risk of invasive breast cancer, but BCRAT is based, in part, on data from women of other races and ethnicities. The new model presented in this study is based on nativity-specific (United States–born vs foreign-born) case-control data, incidence, and competing mortality rates in Hispanic women. The study (abstract A09) was presented recently at the American Association for Cancer Research conference on The Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved, held in November 13–16 in Atlanta, Georgia.
Study Methodology
The researchers used data from two U.S. population–based case-control studies: the San Francisco Bay Area Breast Cancer Study (SFBCS) and the 4-Corners Breast Cancer Study (4-CBCS). Data from 1,086 Hispanic women with breast cancer (533 United States–born and 553 foreign-born) and 1,411 women without breast cancer (controls: 464 United States–born and 947 foreign-born) in the SFBCS were used to estimate relative risks (RR) and attributable risk, separately for United States–born and foreign-born women.
Nativity-specific absolute risks were estimated by combining relative risk and attributable risk information from the SFBCS with nativity-specific invasive breast cancer incidence and competing mortality rates from the California Cancer Registry and the NCI’s Surveillance, Epidemiology, and End Results (SEER) Program, respectively.
The model includes separate calculations for United States–born and foreign-born Hispanic women. The researchers evaluated the relative risk feature by comparing the model relative risks with those estimated for Hispanic women in data from the 4-CBCS (cases = 731, controls = 836).
Data from Hispanic women in the Women’s Health Initiative (WHI) were used to assess model calibration and discriminatory accuracy by estimating the ratio of observed to expected number of breast cancers (O/E ratio) and area under the curve (AUC), respectively.
Study Findings
Risk factors for the United States–born Hispanic model included age at first full-term pregnancy (RR = 1.26), biopsy for benign breast disease (RR = 1.10), and family history of breast cancer (RR = 1.18); risk factors for the foreign-born Hispanic model included age at first full-term pregnancy (RR = 1.60), age at menarche (RR = 1.30), biopsy for benign breast disease (RR = 1.62), and family history of breast cancer (RR = 2.48).
For most United States–born Hispanic women, the model estimated lower risk projections than the BCRAT; for foreign-born Hispanic women, the model estimated higher risk projections than the BCRAT in most instances. There were no significant differences between relative risks estimated from 4-CBCS and those used in the United States–born Hispanic model; however, the RRs used in the foreign-born Hispanic model were significantly higher than those from 4-CBCS (P < 0.05). The model was well calibrated for United States–born women (O/E ratio = 1.07; 95% confidence interval (CI): 0.82–1.40) but overestimated the risk in foreign-born women (O/E ratio = 0.66; 95% CI: 0.41–1.06), in independent data from the WHI. However, overestimation of risk in WHI foreign-born Hispanic women (with only 17 cases) was not statistically significant. The discriminatory accuracy of the model was modest for both United States–born Hispanics (AUC = 0.564) and foreign-born Hispanics (AUC = 0.625).
“This is the first absolute risk model for Hispanic women that is based entirely on data from Hispanic women. A unique feature of the model is the incorporation of nativity-specific SEER incidence rates, which are lower in foreign-born than in U.S.-born Hispanic women. Although the model has been evaluated in independent datasets, further studies in Hispanic women are warranted to evaluate its validity,” concluded the researchers.
The study was funded by the National Cancer Institute.
Matthew P. Banegas, PhD, MPH, declared no potential conflicts of interest.
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