High-dose cyclophosphamide, thiotepa and hydroxyurea with autologous hematopoietic stem cell rescue: an effective consolidation chemotherapy regimen for early metastatic breast cancer.

Phase I and II trials have demonstrated that high-dose chemotherapy with autologous hematopoietic stem cell rescue is effective 'consolidation' chemotherapy for patients with responding metastatic breast cancer. In this study 26 women with metastatic breast cancer responding to lower dose combination chemotherapy were treated with 18 g/m2 of hydroxyurea added to the widely used combination of cyclophosphamide (CY) 6 g/m2 and thiotepa 600 mg/m2. Hematopoietic stem cell support was provided in the form of previously collected cryopreserved marrow or peripheral blood stem cells if there were malignant cells in the marrow. The patients ranged in age from 25 to 51 years with a median of 43 years. Three patients (12%) died of toxicity, one from Candida pneumonia and the other two from pulmonary and central nervous system bleeding secondary to platelet consumption associated with high fever and renal dysfunction, a syndrome we have seen with approximately the same frequency as a complication of other 'marrow transplant level' chemotherapy. The 1 and 2 year progression-free survivals are projected to be 42% and 27%, respectively. Patients in complete remission or with only residual radiographic abnormalities in bone prior to this therapy had 67% and 58% 1 and 2 year progression-free survival probabilities. High-dose hydroxyurea can safely be added to the CY and thiotepa combination.