The effect of sex hormones and tamoxifen on the growth of human gastric and colorectal cancer cell lines.

The authors studied the effect of serial concentrations of estradiol, 4-hydroxytamoxifen with estradiol, and 5-dihydrotestosterone on cell lines derived from human gastric and colorectal cancers. Significant stimulation of the gastric and 2 colorectal cell lines occurred at physiologic concentrations of estradiol. Addition of the active metabolite of the estrogen-receptor blocker/partial-agonist 4-hydroxytamoxifen had a stimulating effect on the growth rate of the gastric cell lines. The androgen, 5-dihydrotestosterone, had a modest inhibitory effect on the two gastric cell lines and two of the colorectal cell lines, and a stimulating effect on two further cell lines.