ASPO Abstracts
Family history and family structure in the Carolina Breast Cancer Study
Category: Early Detection & Risk Prediction, Early Detection & Risk Prediction
Conference Year: 2018
Abstract Body:
The majority of studies that have examined the relationship between family history and breast cancer risk have done so using a yes/no family history variable, a classification method that does not take into account family structure. Using the Carolina Breast Cancer Study (CBCS) Phases 1&2, a large diverse population-based case control study, we examined the utility of a quantitative measure of family history, a family history rate score (FHRS), that accounts for age at diagnosis, number of affected female first degree relatives, and total number of female first degree relatives. Multivariate logistic regression models were used to calculate odds ratios and 95% confidence intervals, overall and stratified by age, race, and tumor characteristics. Among cases, FHRS was higher for White vs. African-American (2.89 vs. 1.91, p=0.0005) women and women < 50 years old vs. women 50 (2.95 vs. 2.00, p=0.009). This was in contrast to using a yes/no measure of family history, which did not show statistically significant differences by race or age. Observed differences in FHRS by age and race are in part due to familial time at risk, which made up the denominator of the score; both White and younger women had less familial time at risk. We also observed that compared to White women, African-American women were more likely to have “inadequate family history” (OR=2.39, 95% C.I.: 1.89-3.03), a measure which reflects lack of family history information for first degree relatives. Stratification on age, race, ER or triple negative status did not modify the risk associated with binary family history or FHRS. These data suggest that family history is an important risk factor for African-American and White women alike and is associated with different breast cancer subtypes, whether described as the presence vs. absence of family history or with a more nuanced measure. In addition, this study highlights how differences in family structure by age or race can affect measures of family history.
Keywords: Family history Family structure Breast cancer risk