Flow cytometric analysis of human breast tumors and assessment of in vitro chemosensitivity by clonogenic assays.

We report a double-agar clonogenic system adapted to human breast cancer. We optimized the conditions for cell growth and clonogenicity with respect to hormones (insulin, estradiol, progesterone) and components of the extracellular matrix (collagen, laminin and fibronectin). Using our experimental improvements, 67% of the breast tumor samples received were grown successfully. Tests on 21 tumors with three agents: Doxorubicin, Methotrexate and 5-Fluorouracil permit objective discrimination of the in vitro pharmacosensitivity of human breast tumors. Flow cytometric analysis reveal that 64% of the tumors were diploid and 36% were aneuploid. The aneuploid tumors grew better in the double agar layer system used for the clonogenic assay. The diploid tumors were especially rich in estrogen (ER+) and progesterone (PR+) receptors whereas the aneuploid tumors were mostly estrogen and progesterone receptors negative (ER-/PR-). Finally, we noted no difference in drug responsiveness depending on the tumor ploidy and steroid receptor content.