Antiestrogen therapy for breast cancer: current strategies and potential causes for therapeutic failure.

There is an enormous literature that supports the use of tamoxifen as the treatment of choice for breast cancer. However, preliminary evidence suggests that long-term treatment with tamoxifen may expose the women to an increased risk of liver and endometrial cancer. This is probably only of concern to young women with stage I (node negative) disease. It remains to be seen whether any of the new strategies, including the new antiestrogens discussed here and novel endocrine therapies, will prove any better as an antitumor treatment. Treatments will probably be directed initially at treating patients after tamoxifen failure and ultimately at treating hormone-independent cancers. These therapies may involve the autocrine growth factors produced by breast cancer cells as potential targets. Such development of novel treatments will be extremely beneficial to these women, who face a worrying lack of therapeutic opportunities, with the exception of chemotherapy.