Growth Effects of Tamoxifen and Estradiol on Laryngeal Carcinoma Cell Lines

OBJECTIVES: We tested the in vitro and in vivo growth effects of estradiol and tamoxifen citrate to determine whether patients with laryngeal carcinoma could benefit from antiestrogen therapy as demonstrated for cancers of other estrogen-responsive organs. DESIGN: A comparison of growth effects of the hormones relative to controls by using a tetrazolium dye reduction assay and nude mice. MATERIALS: Two estrogen-positive laryngeal carcinoma cell lines (UMSCC5 and UMSCC11B) and athymic mice were used. RESULTS: There were marked growth inhibitory effects of tamoxifen alone in concentrations of 3 to 8 mumol/L on both cell lines. There were no in vitro growth effects of estradiol-17 beta alone in concentrations of 0.1 to 9.6 mumol/L, but there was antagonism of the estradiol to the growth inhibitory effects of tamoxifen. In athymic mice, estradiol markedly stimulated the growth of UMSCC5, whereas tamoxifen inhibited growth. CONCLUSIONS: These results support the concept of chemotherapeutic growth inhibition of estrogen receptor-positive laryngeal cancer with antiestrogens.