Effects of hormonal growth factors on colony formation and chemosensitivity of human tumors in agarose.

Because low plating efficiencies of most human cancers severely limit the number of successful chemosensitivity tests that can be performed, we studied the growth-enhancing effects of hormonal growth factors on a variety of solid tumors. Dose-response studies with progesterone and estradiol indicated no benefit from adding these substances to the culture medium. This was true whether progesterone or estradiol was used alone or in the presence of other hormones. By contrast, epidermal growth factor (EGF) at concentrations from 10 to 100 ng/ml increased colony numbers up to 10-fold. Although insulin, hydrocortisone, and EGF used alone could either stimulate or inhibit the growth of specific tumors, the combination of all three (hormone mixture or HM) was always at least as good and usually better than any individual component in increasing cloning efficiency. HM-supplemented medium gave significantly increased colony counts in 41/46 tumors. Sensitivity to anticancer drugs was not changed in 63 paired drug tests.