Purpose: The coronavirus disease-2019 (COVID-19) pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, has delayed medical consultations, especially for patients receiving intravenous anti-cancer therapy. We aim to investigate alterations in immune function among breast cancer patients who experience delayed intravenous therapy due to SARS-CoV-2 infection.
Patients and Methods: We performed an observational investigation of breast cancer patients in Nanjing Drum Tower Hospital from December 27, 2022, to January 20, 2023. Patients who recovered from SARS-CoV-2 infection were eligible for enrollment. Peripheral blood samples were taken prior to the restart of intravenous anti-cancer therapy to examine hematologic parameters.
Results: A total of 131 patients were included in the final analysis. Cough (74.0%), fever (62.6%), and expectoration (46.6%) were identified as the most presenting symptoms of SARS-CoV-2 infection in breast cancer. The average nucleic acid conversion time and delayed treatment time was 13.4 days and 13.9 days, respectively. The patients > 60 years old experienced prolonged nucleic acid conversion time (P = 0.017) and delayed treatment time (P = 0.028) compared to those <= 60 years old. Dysregulated lymphocyte subsets and cytokines were found post-SARS-CoV-2 infection. Treatment-related adverse events of grade 3 or 4 occurred in 7.6% after resuming intravenous anti-cancer therapy.
Conclusion: Our findings reveal that the SARS-CoV-2 infection led to imbalanced immune responses and postponed intravenous anti-cancer therapy in breast cancer. The safety report encourages timely resumption of intravenous anti-cancer therapy after adequately weighing the risks and benefits.

Keywords: COVID-19 pandemic, SARS-CoV-2 infection, breast cancer, immune responses, anti-cancer therapy