[Simple treatment of tumor-induced hypercalcemia: i.v. aminohydroxypropylidene biphosphonate]

The treatment of tumour-induced hypercalcemia (HCa) by diphosphonates appears to be safe and reliable with very mild side effects. We have tested APD as sole treatment in 14 patients with cancer and symptomatic HCa. APD was given i.v. in a dose of 0.38 +/- 0.03 mg/kg BW/day until two subsequent normal plasma calcium (Ca) levels were obtained (Ca determined daily). The mean duration of treatment was 5.56 +/- 1.9 (4 to 11 days). As expected, there was a significant correlation between initial Ca and duration of therapy (p less than 0.001). Mean Ca fell from 3.38 +/- 0.19 mmol/l before APD to 2.43 +/- 0.09 after 4 days of treatment and remained normal four weeks after the start of treatment. Four patients relapsed 11 to 31 days after the end of treatment during a one-month follow-up. This recurrence did not depend on initial Ca, length of treatment and duration of remission. Two of these patients were treated successfully with a second course of APD, while in the other two no further treatment was undertaken. Both mean UCa and UHydroxyproline decreased significantly when measured seven days after the beginning of the treatment. Plasma PTH values remained in the normal range, while NcAMP rose significantly after a week of treatment from low to normal values. Plasma phosphorus decreased significantly (p less than 0.005) during the treatment while TRP % increased, suggesting a positive phosphorus balance. We conclude that short treatments with APD of tumour-induced HCa are effective and sufficiently sustained, even if they are interrupted as soon as normal Ca is obtained.