Tumor lysis syndrome, a complication of anticancer chemotherapy, results from rapid lysis of malignant cells. We report tumor lysis syndrome in a patient treated with trastuzumab for metastatic breast carcinoma. A 69-year-old woman was diagnosed with multiple liver metastases 1 month after mastectomy. As her liver functions had deteriorated, chemotherapeutic agents were contraindicated and she was treated with trastuzumab alone. On day 6 of the first course of trastuzumab, she developed tumor lysis syndrome. As her liver functions showed deterioration due to multiple hepatic metastases, hemodialysis was contraindicated. Acute renal failure worsened and she died 11 days after the administration of trastuzumab.
Keywords: Breast cancer; Molecular targeting drug; Solid tumor; Trastuzumab; Tumor lysis syndrome.