RESUMO
Radical surgery in malignant bone tumors can either be limited by anatomical structures or seems inadequate in the palliative stabilization of bone metastases. Incomplete removal of the tumor and stabilization by compound osteosynthesis or endoprosthesis contains two problems: 1) the wide spread of malignant cells by manipulation in the tumor bearing area; 2) progressive destruction of bone due to remaining tumor. To overcome these problems we developed methotrexate bone cement (MTX-Palacos) with the aim to obtain high local concentrations of methotrexate in order to destroy remaining tumor cells and avoid systemic side effects. In vitro studies showed that methotrexate is released continuously from this cement without relevant changes of its biomechanical properties. Animal studies with transplanted osteosarcomas and mamma carcinomas in mice showed a considerable decrease of tumor growth when a plug of MTX-Palacos was inserted in the center of the tumor. Histological findings showed that in the surroundings of the plug the tumor was destroyed considerably contrary to normal bone cement which had no effect on the tumor at all. The results are discussed with regard to clinical application of MTX-Palacos.