The role of granulocyte-macrophage colony-stimulating factor in the treatment of germ cell tumors. German Testicular Cancer Study Group.

Hematopoietic growth factors, such as granulocyte-macrophage colony-stimulating factor (GM-CSF), may gain increasing importance in the treatment of patients with malignant germ cell tumors. For patients with far advanced testicular cancer, who only have a chance of long-term cure in the range of 40% to 50% by standard induction chemotherapy, the German Testicular Cancer Study Group has shown that the application of GM-CSF after PEI chemotherapy has allowed the increase of dose intensity of this three-drug regimen by a factor of 1.4. In 75 evaluable patients an overall survival rate of 79% after a median follow-up of 27 months was achieved. The dose-limiting toxicity of this stepwise dose escalation protocol of the PEI regimen was severe mucositis/enteritis (World Health Organization [WHO] degrees 3/degrees 4) in 33% of the patients and prolonged thrombocytopenia (< 20,000/microL for more than 10 days). In future trials, hematopoietic growth factors will be used in the treatment of far-advanced testicular cancer to generate peripheral blood stem cells (PBSC) that can be used to overcome both granulocytopenia and thrombocytopenia. This approach with the use of PBSC and hematopoietic growth factors will allow us to apply multiple cycles of up-front dose-intensified PEI chemotherapy in this unfavorable subgroup of patients. However, with the establishment of an optimal hematopoietic support in these studies, the value of dose-intensified chemotherapy in advanced testicular cancer will have to be tested against standard dose regimens in prospective randomized trials.