[A Case of Chemotherapy-Associated Thrombosis during Neoadjuvant Chemotherapy for Breast Cancer].

Cancer-associated thrombosis is a serious complication of malignancy. Here, we report a case of concurrent arterial and venous thrombosis that occurred during neoadjuvant chemotherapy for breast cancer. A 72-year-old woman presented at the emergency department with malaise and movement difficulties after completing 2 cycles of dose-dense AC therapy. Contrast-enhanced computed tomography revealed thrombi in the aortic arch and left subclavian vein as well as splenic infarction. The patient was initially treated with intravenous heparin and was subsequently switched to edoxaban, which resulted in thrombus resolution. Hormone therapy was administered followed by surgery for breast cancer, and the patient's postoperative course was favorable. Thrombosis in this case was due to hypercoagulability induced by cancer and chemotherapy. Careful monitoring of thrombotic events is required during cancer treatment.