Arterial thrombosis associated with adjuvant chemotherapy for breast carcinoma: a Cancer and Leukemia Group B Study.

Multiagent chemotherapy and chemohormonal therapy for breast cancer are associated with an increased risk for venous thromboembolic complications. We observed instances of arterial thrombosis in two studies of breast cancer involving multiagent chemotherapy for stages II and III disease. Our purpose in this study was to determine the incidence of this complication and whether it appeared to be related to the chemotherapy or was a random event. Episodes of arterial thrombotic events were identified from record reviews of 1,014 assessable patients with breast cancer entered on two Cancer and Leukemia Group B protocols. Details of the kind of arterial event, when it occurred, the outcome, and the occurrence of metastases were analyzed. Thirteen (1.3%) patients had an arterial thrombosis: six (5.3%) of 113 patients with stage III disease and seven (0.8%) of 901 patients with stage II disease. Four of these patients had a peripheral arterial thrombosis and nine had strokes (four were fatal). All these events occurred while the patients were receiving adjuvant chemotherapy. Only one additional arterial event (a stroke approximately four years later) has occurred in this patient group after chemotherapy was completed. Arterial thrombosis is also associated with multiagent chemotherapy in patients with breast cancer. The mechanism is unknown.