Effects of estrogen and tamoxifen on growth of human vestibular schwannomas in the nude mouse

Vestibular schwannomas have been noted to have increased frequency and aggr essivity in female patients, suggesting a possible role of estrogen. This s tudy evaluated the effects of estrogen and tamoxifen on the growth of human vestibular schwannoma tissue implanted in subcutaneous pockets of nude mic e. Animals were implanted with 1 of 3 human vestibular schwannomas and obse rved for 28 days. Mice were then separated into 3 treatment groups: control s, estrogen (receiving 1.7 mg of 17B-estradiol), and estrogen + tamoxifen ( receiving 1.7 mg of 17B-estradiol + 10 mg of tamoxifen), and treated for 28 days. Mice treated with estrogen showed increased growth that was statisti cally significant (P < 0.05) when compared with that of both the controls a nd the animals treated with estrogen + tamoxifen. Controls and animals trea ted with estrogen + tamoxifen showed a general trend of decreased volume du ring the treatment period. These early results support the hypothesis that estrogen modulates the growth of vestibular schwannomas in the nude mouse m odel and that these effects can be blocked by tamoxifen administration.