Two Cases of Malignancy-Associated Hypercalcemia Treated with Mithramycin

The hypocalcemic effect of mithramycin, an antitumor antibiotic,was studied in two consecutive hypercalcemic patients with malignancy.Case 1 was a 60-year-old woman with advanced breast cancer.Severe, generalized bone metastasis seemed to be the cause ofthe hypercalcemia. Serum calcium levels reached 14.6mg/dl (ionizedcalcium 3.84 mEq/I) despite continued therapy with saline (5liters/day) with frosemide (60mg/day, intravenously), high dosesof elcatonin (up to 440 MRC units/day) and prednisolone (30mg/day). Case 2 was a 49-year-old woman with recurrence of ovariancancer. Bone metastasis was not found on X-ray films. Hypercalcemiawas progressive in spite of extensive treatments with saline(2 liters/day) with frosemide (40 mg/day), indomethacin (150mg/day), elcatonin (160 MRC units/day) and prednisolone (30mg/day). Meantime, serum calcium rose to 14.6mg/dl (ionizedcalcium 3.57 mEq/I). In both cases, mithramycin (1.25 mg) wasthen administered intravenously. Serum calcium levels droppedto 9.6 and 9.4 mg/dl two days after the administration of mithramycinin case 1 and case 2, respectively. These observations indicate that mithramycin is more effectivethan any other drug tested for the treatment of hypercalcemiacaused by malignancy irrespective of the presence or absenceof bone metastasis. Therefore, it should be widely used forhypercalcemic emergency.