Magnesium alterations and pharmacokinetic data in gallium-treated lung cancer patients.

The dose of gallium chloride required to inhibit tumor growth after oral and chronic administration depends on the stage of the cancer disease and of the type of metastases. A dose regimen of 800 mg/24 h of gallium chloride will provide serum gallium concentrations greater than or equal to 600 micrograms/l in lung cancer patients with a small and limited disease. A dose of 1,400 mg/24 h is well tolerated in metastatic patients but may not be high enough to reach the desired serum gallium concentrations especially in patients with bone metastases. Radiotherapy and/or a chemotherapy will permit one to increase the serum gallium concentrations and the tumor gallium uptake by reducing the volume of the tumor. After chronic, oral administration of gallium a decrease in RBC Mg is noted. To avoid the Mg deficiency, the treatment must not be interrupted and may perhaps be decreased with care and slowly without resulting in a decrease of the serum gallium concentrations provided the treatment has been prolonged over a sufficient time to enable one to induce intratumor biological modifications and a decrease in the number of the malignant cells. Acute pharmacokinetic data are related to the histologic type of the tumor and may not be used to predict the serum gallium concentrations after chronic administration. The serum gallium concentrations required to inhibit the tumor growth may be higher in small cell lung carcinomas than in nonsmall cell lung carcinomas. Frequent Mg and Ga blood determinations are necessary to manage effective gallium treatment.