UC Berkeley

Background: Breast cancer is the leading cancer diagnosis and the second leading cause of cancer-related death in the United States. However, the overall mortality rate declined more than 42% over the last 30 years due to advances in treatment and screening. Despite these advancements, the breast cancer mortality rate for Black women is persistently higher than any other group with a 41% gap in survival compared to White women. The cause of this disparity is complex and partially attributed to non-modifiable factors such as tumor biology and modifiable factors such as access to quality breast cancer treatment, reductions in obesity, and other chronic conditions. The purpose of this research is to examine the contributions of body mass index, comorbidity, and hospital characteristics to the breast cancer mortality disparity between Black and White women.

Methods: This dissertation assesses the contributions of comorbidity, obesity, and hospital characteristics to breast cancer mortality disparities between Black and White women. Chapter 1 provides an overview of breast cancer mortality trends, a review of the literature on the associations of modifiable factors associated with breast cancer mortality and presents the questions and hypotheses for the proceeding chapters. Chapter 2 is a systematic review of peer-reviewed articles to evaluate comorbidity as a primary contributor to breast cancer mortality disparities between Black and White women. Chapter 3 presents the findings of the evaluation of body mass index as a modifier of breast cancer and all-cause mortality disparities between Black and White women using a historical breast cancer cohort dataset. Chapter 5 presents findings from our study of the associations between hospital characteristics, breast cancer surgical volume and hospital area-level poverty, and breast cancer mortality and all-cause mortality. The final chapter provides a summary of our findings and suggestions for future research.

Significance: Identifying and addressing modifiable risk factors for breast cancer mortality is key to narrowing the breast cancer mortality gap between Black and White women. Obesity, comorbidity, and hospital quality are three such modifiable factors. This research aims to contribute to existing knowledge and elucidate the roles of obesity, comorbidity, and hospital characteristics to adverse breast cancer outcomes among Black women.