Cultivation of human breast carcinoma in soft agar. Experience with 237 fresh tumour specimens.

A total of 237 breast carcinomas have been studied with the Courtenay-Mills (C-M) soft agar method. Cell yields and plating efficiencies (PE) were recorded after various enzyme treatments. The highest cell yields and PEs were obtained with the combination of collagenase 0.5%, hyaluronidase 1000 IE ml-1 and DNase 0.1% and an incubation time of 2 h. Eighty percent of the specimens gave greater than 10 colonies, and 60% formed greater than 30 colonies permitting chemosensitivity studies. The C-M method gave significantly higher PEs than the Hamburger-Salmon (H-S) method. Hormone supplements (insulin, oestradiol, progesterone, hydrocortisone) and also reduced agar concentrations (less than 0.3%) gave marginal stimulation of colony formation. In chemosensitivity studies involving doxorubicin, vincristine and 4-OOH-cyclophosphamide, the C-M method gave dose-response relationships without plateaus.