A case of bone marrow carcinosis from gastric cancer that presented hypocalcemia caused by zoledronic acid during the treatment of methotrexate/5-fluorouracil sequential therapy

The case was a 64-year-old man. He was diagnosed as gastric cancer, lymph node metastases, brain matastases, bone marrow carcinosis, and disseminated intravascular coagulation (DIC). He was started on methotrexate (MTX)/5-fluorouracil (5-FU) sequential therapy (weekly administration of MTX (100 mg/m², iv bolus) followed by 5-FU (600 mg/m², iv bolus) with a 3 h interval). DIC was resolved, and the tumor marker decreased remarkably. Four weeks later, he received zoledronic acid 4 mg to prevent skeletal complication. Next day, fatigue and anorexia onset. Six days later, laboratory data showed severe hypocalcemia. He was started on calcium gluconate 3.4 g/day. The calcium level was normalized in twelve days, and the symptoms were improved. MTX/5-FU therapy was resumed, and his condition remained stable. However, after the ninth dosage, he developed fatigue and low back pain, and the DIC relapsed. We started paclitaxel therapy. But it was not effective and he died ten days later. It was considered that careful attention to hypocalcemia is necessary when we use zoledronic acid for the bone marrow carcinosis treated with chemotherapy.