ABSTRACT
Background: In high-risk estrogen-receptor positive, HER2 positive, or triple negative breast cancer (BC), chemotherapy can increase cure rates in early-stage disease and prolong survival in setting of advanced disease. Real world data specific to BC is needed to counsel patients (pts) with BC on their risk for SARS-CoV-2 infection and mortality in the context of the SARS-CoV-2 pandemic. Methods: In this retrospective study, we abstracted clinical data including demographics, tumor histology, cancer treatment, and COVID-19 testing results status from the electronic medical record of 3778 BC patients who received cancer care from 02/01/2020 - 05/01/2020 in New York City at our cancer center. The primary endpoint of the study was incidence of SARS-CoV-2 infection by treatment type (cytotoxic chemotherapy (CT) vs non-cytotoxic therapies (endocrine and/or HER2 directed therapy (E/H)) diagnosed by either serology, RT-PCR, or documented clinical diagnosis. Probability of Treatment Weighting (IPTW) and Mann-Whitney Test were used to assess risk of SARS-CoV-2 infection by treatment and assess outcomes based on oncologic and non-oncologic risk factors respectively. Results: 3062 patients met inclusion criteria with 379 pts in CT, 2343 pts in E/H and 340 in NT groups. During study period 641 patients (20.9%) were tested by either PCR or serology with 64 patients (2.1%) diagnosed with COVID-19. All pts who tested positive by PCR and subsequently had serology testing were positive for IgG. The weighted risk of SARS-COV-2 infection was 3.5% in CT vs. 2.7% in E/H (p=0.523). 27 patients (0.9%) expired over follow up, with 10 deaths attributed to SARS-CoV-2 infection. The weighted risk for death was 0.7% with CT vs. 0.1% with E/H, p=0.24 (Table A). Age, BMI,CCI and advanced cancer stage were associated with increased mortality following SARS-CoV-2 infection (Table). Conclusions: CT was not associated with increased risk of infection with SARS-CoV-2 infection or death following infection. BC cancer treatment, including CT, can be safely administered with enhanced infectious precautions and should not be withheld particularly when given for curative intent.