BackgroundThe worldwide spread of the coronavirus disease 2019 (COVID-19) has impacted the treatment of cancer patients. Treatment changes can negatively affect patients’ prognosis and may be psychologically burdensome.ObjectiveThe aim of this study was to explore whether COVID-19–related treatment changes (delays, cancellations, changes) influenced fear of cancer recurrence, anxiety, and depression in breast cancer patients.MethodsA convenience sample (n = 154) of patients who were diagnosed with breast cancer no longer than 2 years ago was obtained from an online community and social network site. The survey content included COVID-19–related treatment experiences and psychological status. The data were analyzed using descriptive statistics, χ2 test, independent t test, and analysis of variance.ResultsTwenty-nine patients (18.8%) had experienced COVID-19–related treatment changes, and changes of the treatment plan had a significant correlation with depression (t = 2.000, P = .047). Fear of cancer recurrence was high (mean score, 84.31 ± 24.23). Fifteen percent had moderate to severe levels of anxiety, and 24.7% had moderate to severe levels of depression. Narrative reports also identified COVID-19–related unforeseen costs.ConclusionIn the midst of the COVID-19 pandemic, breast cancer patients experienced treatment changes, and changes in treatment plans were significantly associated with depression. Fear of recurrence, anxiety, and depression were found at high levels.Implications for PracticeOncology nurses should assess the psychological status of cancer patients in the early survivorship phase who appear to be especially vulnerable during the COVID-19 pandemic. Oncology nurses can also monitor whether patients are receiving timely supportive care to alleviate fears and anxiety and assess financial needs for COVID-19–related costs.