Comparison of progenitor cell collection on day 4 or day 5 after steady-state stimulation with G-CSF alone in breast cancer patients: Influence on CD34(+) cell yield, subpopulation, and breast cancer cell contamination

To determine the influence of apheresis timing on CD34(+) cell yield, subpo pulation, and breast cancer cell contamination, 48 women with breast cancer were stimulated from steady-state hematopoiesis in a prospective but nonra ndomized study with 2 x 5 mu g/kg G-CSF s.c. alone, and apheresis was start ed either on day 4 (n = 24) or day 5 (n = 24). Forty-eight women with breas t cancer (stage II/III, n = 30; stage IV; n = 12; inflammatory, n = 6) and a median age of 44 years were well balanced between the two groups. In grou p I, aphersis was started on day 4 and additionally performed on day 5 afte r G-CSF stimulation, and in group II, apheresis was started on day 5. CD34( +) cell count and CD34(+) cell subpopulation were determined according to i nternational criteria. Breast cancer cell contamination was detected by imm unocytology. The median CD34(+) cell harvest on day 4 was 3.3 x 10(6)/kg bo dy weight (range 0.5-12.8) and 6 x 10(6)/kg BW (range 0.3-30) for patients starting on day 5 (p = 0.01). Those patients starting on day 4 achieved a m edian CD34(+) cell count of 4 x 10(6)/kg (range 0.7-13) on day 5 (NS). Twen ty-one percent of group I and 71% of group II achieved >5 x 10(6)/kg BW CD3 4(+) cells in the first apheresis, whereas <2.5 x 10(6)/kg BW CD34(+) cells in the first apheresis were observed in 38% of group I and 16% of group II . No differences were observed between the CD34(+) cell subpopulations, CD3 4(+)/CD38(+) (10.5% versus 10.5%) and CD34(+)/Thy1(+) (1.5% versus 1.8%). T he CD34(+) cell harvest from consecutive collecting on days 4 and 5 was nea rly identical to the harvest starting on day 5 (6.4 versus 6 x 10(6)/kg). C ollecting CD34(+) progenitor cells after stimulation with G-CSF alone on da y 5 results in a significantly higher cell yield than starting collecting o n day 4. No differences in respect to breast cancer cell contamination and CD34(+) cell subpopulation were observed.