Breast cancer is the most common malignancy and the second leading cause of cancer death among women in the U.S. Although the racial disparities in breast cancer mortality have been well documented, many questions remain unanswered in understanding these racial disparity gaps. In this dissertation, I conducted three research projects to enhance our understanding of the racial disparities in the survival and quality of life of patients with breast cancer. The first chapter aimed to facilitate clinical decision-making. In this chapter, we developed and validated a machine learning model (https://huolab.cri.uchicago.edu/sample-apps/pcrmodel/) to predict pathologic complete response following neoadjuvant chemotherapy in breast cancer patients using pre-treatment clinicopathological features alone. Utilizing data from the National Cancer Data Base, the machine learning model demonstrated robust discrimination and calibration capabilities in both the validation set and the external testing set. The model performed best among patients with hormone receptor positive/ human epidermal growth factor receptor 2 negative diseases. It had the potential to facilitate clinical decision-making by identifying patients who were less likely to achieve pathologic complete response to consider alternative treatment strategies over chemotherapy, which might optimize treatment outcomes while reducing undue toxicity. The second chapter focused on understanding the metabolic health of patients with breast cancer. We conducted a retrospective cohort study in the Chicago Multiethnic Epidemiologic Breast Cancer Cohort to examine the association between metabolic syndrome and breast cancer treatment. We did not find that breast cancer patients were at a higher risk of developing metabolic syndrome after treatment compared with controls. In addition, we observed evidence suggesting that the glycemic control in breast cancer patients with diabetes might be affected after treatment. The third chapter investigated the new challenges brought by the COVID-19 pandemic on the quality of life of breast cancer patients and survivors. To address this question, we conducted a longitudinal survey study among the breast cancer patients and survivors enrolled in the Chicago Multiethnic Epidemiologic Breast Cancer Cohort. Our findings suggested that, as the pandemic subsided, the isolation and stress levels of patients have improved in general, while slightly varying across different racial/ethnic groups who might possess different coping capacities. Through these three comprehensive research projects spanning across the entire breast cancer continuum, this dissertation provided valuable insights to bridge the racial disparity gaps in the survival and quality of life of patients with breast cancer.