GROWTH EFFECTS OF TAMOXIFEN AND ESTRADIOL ON LARYNGEAL CARCINOMA CELL-LINES

Objectives: We tested the in vitro and in vivo growth effects of estra diol and tamoxifen citrate to determine whether patients with laryngea l carcinoma could benefit from antiestrogen therapy as demonstrated fo r cancers of other estrogen-responsive organs. Design: A comparison of growth effects of the hormones relative to controls by using a tetraz olium dye reduction assay and nude mice. Materials: Two estrogen-posit ive laryngeal carcinoma cell lines (UMSCC5; and UMSCC11B) and athymic mice were used. Results: There were marked growth inhibitory effects o f tamoxifen alone in concentrations of 3 to 8 mu mol/L on both cell li nes. There were no in vitro growth effects of estradiol-17 beta alone in concentrations of 0.1 to 9.6 mu mol/L, but there was antagonism of the estradiol to the growth inhibitory effects of tamoxifen. In athymi c mice, estradiol markedly stimulated the growth of UMSCC5, whereas ta moxifen inhibited growth. Conclusions: These results support the conce pt of chemotherapeutic growth inhibition of estrogen receptor-positive laryngeal cancer with antiestrogens.