Minimal tumor contamination of hematopoietic harvests from breast cancer patients can be easily detected by liquid culture assay

Background Recurrence after PBSC transplantation in breast cancer (BC) patients may be related to the reinfusion of tumor cells contaminating the graft. We have developed a liquid culture (LC) method for the identification of viable epi thelial tumor cells in PBSC collections. Methods Mononuclear fraction from PBSC harvests of BC patients undergoing high dose chemotherapy (HDC) (adjuvant setting n = 60, metastatic disease n = 30) we re seeded in petri dishes containing round cover slips. Cells were cultured for 3 weeks then cover slips were stained with the pan-cytokeratin A45-B/B 3 mAb and scored under a light microscope. Samples were considered positive when more than one adherent cell or a cluster of cells staining bright red was present Results were compared with those obtained on cytospins prepare d directly from the PBSC harvest. Specificity of the method was tested on l ymphoma patients, collections: all were negative The sensitivity, evaluated by serial dilations of CG5 BC cell line was 1 epithelial cell in 10(6) mon onuclear cells. Results The percentage of positivity was superimposable in the two groups (adjuvant 25% metastatic 24%). However; a significantly higher proportion of positiv e samples from metastatic vs adjuvant patients has shown the presence of tu mor clusters (86% vs 33%, p = 0.063). In 21% of all samples a discrepancy w ith the results obtained by immunocytochemical analysis (ICC) was found, mo stly due too liquid-culture-positive/ICC-negative PBSCs. Discussion Our data suggest that LC assay may enhance the identification of viable dis seminated epithelial tumor cells in PBSC grafts and might provide insights about their growth capacity.