[A Case of COVID-19 Infection during Postoperative Chemotherapy for Breast Cancer Treated with Antibody Cocktail Therapy to Prevent Disease Aggravation].

The outbreak of COVID-19 has caused a global pandemic, and it has been reported that patients with cancer are at high risk of developing complications from the disease. However, we believe that prolonged interruption of chemotherapy due to extended COVID-19 treatment is not desirable, given the intensity of cancer treatment. We report a case of COVID-19 infection during postoperative chemotherapy for breast cancer, in which antibody cocktail therapy prevented disease aggravation and delayed breast cancer treatment. The patient is a 45-year-old woman who came to our hospital with a complaint of a right mammary mass. The mass was diagnosed as invasive ductal carcinoma with an ER and PR of 0%, a HER2 score of 1+, and a Ki-67 of 90%. After preoperative chemotherapy, she underwent a right mastectomy and axillary dissection. The pathology result showed non-pCR. The administration of capecitabine was started as adjuvant therapy. On day 8 of cycle 3, she developed a fever in the 39℃ range, and on the next day, a COVID-19 POC gene test confirmed that the patient was positive for infection. On the same day, neutralizing antibody drugs(casirivimab and imdevimab)were administered as antibody cocktail therapy. Two days after treatment(day 11), a blood test showed Grade 3 neutropenia, but there was no recurrence of fever or evidence of pneumonia. After 2 weeks, capecitabine was resumed, and the patient was able to complete 8 cycles of capecitabine therapy without any major complications.