BACKGROUND: As the coronavirus disease 2019 (COVID-19) pandemic continues to spread, it remains unclear how vulnerable populations with preexisting health conditions like cancer have been affected. METHODS: Between July and September of 2020, the authors conducted a cross-sectional study that surveyed 2661 patients with breast cancer who were registered in the Chicago Multiethnic Epidemiologic Breast Cancer Cohort and received 1300 responses (71.5% White patients and 22.4% Black patients). The survey measured the psychosocial well-being of participants before and during the COVID-19 pandemic and examined whether they experienced any type of financial challenges or treatment disruption. RESULTS: The results indicated that feelings of isolation increased significantly during the pandemic. Meanwhile, the overall median isolation/stress score was 1.2 on a scale from 0 (never) to 4 (always), which was not significantly different between White patients and Black patients. One-third of patients experienced some type of financial challenge during this time. Medicaid recipients, of whom almost 80% were Black, were more likely to experience financial challenges. In addition, approximately one-fourth of patients experienced difficulty getting treatment. CONCLUSIONS: This study indicates that the quality of life of patients with breast cancer and their scheduled treatments have been adversely affected during the COVID-19 pandemic. These findings suggest that more support should be provided by hospital centers and the medical research community to patients with cancer during this challenging pandemic. LAY SUMMARY: The authors surveyed patients with breast cancer in Chicago using a questionnaire to examine how their lives have been affected during the coronavirus disease 2019 (COVID-19) pandemic. The results indicate that the lives of patients with breast cancer and their scheduled treatments have been adversely affected during the pandemic. In addition, patients who were covered by Medicaid, most of whom were Black, were more likely to experience financial challenges. The findings suggest that hospital centers and the medical research community should reach out and provide more information to support patients with cancer during this challenging pandemic.