Breast Cancer Endocrine Therapy Complicated by Acute Mesenteric Artery Thrombosis

What happened, in summary

A 54-year-old woman had undergone mastectomy with sentinel lymph-node biopsy for breast cancer about 6 months before an emergency admission. She then completed 4 cycles of paclitaxel and cyclophosphamide and started adjuvant toremifene because the cancer was estrogen receptor-positive.

Two months after starting toremifene, she developed sudden severe left-sided abdominal pain with nausea and vomiting. Emergency imaging showed a clot blocking the superior mesenteric artery. Surgery found about 20 cm of necrotic small intestine, and she required urgent arterial thrombectomy together with removal of the affected bowel. She recovered and was discharged 7 days later.

Toremifene was stopped after the event. The authors considered the endocrine therapy a possible contributor to the arterial thrombosis, while also noting that cancer and prior chemotherapy can themselves increase clotting risk. The breast cancer was being treated in the adjuvant setting without evidence of recurrence. During 1.5 years of follow-up after the emergency, she had no further thrombotic events.