SIMILAR BREAST-CANCER CELL CONTAMINATION OF SINGLE-DAY PERIPHERAL-BLOOD PROGENITOR-CELL COLLECTIONS OBTAINED AFTER PRIMING WITH HEMATOPOIETIC GROWTH-FACTOR ALONE OR AFTER CYCLOPHOSPHAMIDE FOLLOWED BY GROWTH-FACTOR

Purpose: To evaluate tumor-cell contamination of peripheral-blood prog enitor-cell (PBPC) collections obtained after priming with granulocyte colony-stimulating factor (G-CSF). Patients and Methods: Immunocytoch emical (ICC) and tumor clonogenic (TCA) assays were used to analyze tu mor-cell contamination of pretreatment peripheral-blood (PB) and bone marrow (BM) samples, and of PBPC collection samples obtained after pri ming with G-CSF 5 mu g/kg/d for 5 or 7 days in 38 women with advanced breast cancer undergoing high-dose chemotherapy (HDC). Results were co mpared with 37 historical control patients who underwent PBPC mobiliza tion with cyclophosphamide (4 g/m(2)) followed by granulocyte-macropha ge colony-stimulating factor (GM-CSF) 5 mu g/kg/d for 14 days. Results : Before PBPC priming with G-CSF, only one of 37 (3%) PB and four of 3 6 (11%) BM samples held tumor cells detected by ICC, Tumor-cell contam ination of PBPC collections obtained after 5 or 7 days of G-CSF primin g was observed in only three of 38 patients (8%). All patients with tu mor cells detected in the PBPC collection had stage IV disease. Cells with in vitro clonogenic potential were detected only in the pretreatm ent BM sample in one patient, and another two patients had ICC- and TC A-positive PBPC samples despite tumor-negative PB and BM before primin g. These results are similar to those previously reported for PBPC pri med with cyclophosphamide and GM-CSF. Conclusion: In patients with adv anced breast cancer responsive to cytotoxic chemotherapy, tumor-cell c ontamination is not increased in PBPC collected after 5 or 7 days prim ing with G-CSF and appears similar to that seen when PBPC ore primed w ith cyclophosphamide followed by GM-CSF. (C) 1996 by American Society of Clinical Oncology.