Examining Risk Factors for Early-Onset Breast Cancer

Jennifer Grace Taylor, University of South Carolina

Abstract

Introduction: There have been great advancements in screening and in the identifying of risk factors associated with breast cancer, however, there is a lack of information of these factors in women with breast cancer occurring under the age of 45, known as early-onset breast cancer (EOBC). EOBC is often found at later stages, negatively impacting young women’s careers, family planning, and mental health. Additionally, because of the health disparities that exist within the U.S. health care system, women belonging to racial and ethnic groups, specifically young Black women, tend to have poorer outcomes and higher mortality rates of EOBC compared to white women. The examination and comparison of socio-demographics, risk factors, and stages at diagnosis across age and racial/ethnic groups is needed to better understand health inequities and what predisposes women for developing EOBC. Therefore, this proposed dissertation study overall aimed to determine if age of breast cancer diagnosis is dependent upon a woman’s reproductive and pregnancy history using a national public database and conduct a logistic regression analysis of EOBC in South Carolina using a state-wide database stratifying by race and rural versus urban living status. Methods: Using the public database National Health Examination and Nutrition Survey (NHANES), for Specific Aim 1, we examined if age of breast cancer diagnosis was dependent upon available reproductive and pregnancy history variables during survey cycles 2005 to 2018 (n=594). For Specific Aim 2, we conducted a descriptive and logistic regression analyses using a combined health database from South Carolina to determine if stage of breast cancer was dependent upon race, marital status, and rural versus urban county of diagnosis while controlling for age (n=1,394), specifically examining for racial differences and geographical variation. Descriptive statistics, odds ratios (ORs), 95% Confidence Intervals (CIs) and p-values were presented. Results: For Specific Aim 1, out of 594 women diagnosed with BC across all ages, 102 (17%) of women were diagnosed with EOBC. We did not find any statistical significance showing that the pregnancy and reproductive variables we examined are associated with breast cancer. For Specific Aim 2, of women diagnosed with BC in SC between 2011 and 2018, 1,394 were classified as having EOBC. Age was statistically significant when comparing stage 0 to stage 1(OR=0.907, 95% CI: 0.868-0.947; p value= <.0001), 2 (OR=0.923, 95% CI= 0.860-0.991; p value= 0.02), stage 3 (OR= 0.922, 95% CI= 0.881-0.965, p value= 0.02) and stage 4 (OR= 0. 893, 95% CI= 0.838-0.952, p value = 0.0005) showing that older age of diagnosis in women with EOBC in SC is associated with lower odds of being diagnosed with more advanced stages of breast cancer. Conclusion: Although we did not find any statistically significant results, our results from this dissertation do show the need for more future research focusing on young women with EOBC . This includes the creation of thorough assessment tools relating to EOBC, and the identification of risk factors to assist with early detection.