The use of high-dose estrogens for the treatment of breast cancer.
The use of high–dose estrogens for the treatment of breast cancer.
- Pantarhei Oncology BV, Zeist, The Netherlands.
- Pantarhei Oncology BV, Zeist, The Netherlands. Electronic address: email@example.com.
- Department of Endocrinology, University Medical Center Utrecht, The Netherlands.
Estrogens are known to stimulate the growth of breast cancer but they are also an effective treatment for this disease (this has been termed the ‘estrogen paradox’). The fact that estrogens can be an effective treatment for breast cancer is something that has almost been forgotten, whereas the fear for estrogens remains. This paper reviews the use of estrogens for the treatment of breast cancer and identifies possible applications. The data summarised in this review demonstrate that high–dose estrogens are effective for the treatment of advanced breast cancer, both as first-line treatment as well as for treatment after occurrence of endocrine resistance to TAM and AIs. Essential for efficacy is an extended period of estrogen deprivation before the tumour is subject to estrogen treatment (the gap hypothesis). Research on the mechanism of action has shown that apoptosis induced by estrogens is regulated via the estrogen receptor and growth factor signalling pathways. High–dose estrogens have a negative safety image, especially in terms of side-effects and increased rates of cardiovascular disease, but the safety data reviewed in this paper do not give rise to major concerns. Taking into account their side-effect profile together with their observed clinical efficacy, high–dose estrogens should be considered a valuable alternative to chemotherapy in selected patients.
Estradiol as a Targeted, Late-Line Therapy in Metastatic Breast Cancer with Estrogen Receptor Amplification.
- Internal Medicine, UPMC Presbyterian.
- Division of Hematology/Oncology, Magee Women’s Hospital of UPMC.
- Pharmacology and Chemical Biology, University Of Pittsburgh.
Estradiol is a major regulator of growth for the subset of breast cancers that express the estrogen receptor (ER, ESR1). Strategies to block ER action, via reduction of estradiol or direct inhibition of ER, have shown major success in the prevention and treatment of breast cancer. However, most ER-positive (ER+) metastatic breast cancers (MBC) eventually become resistant to these interventions. Interestingly, high dose estrogen can induce apoptosis in breast cancer cell lines, and high-dose estrogen has been used for over 50 years as therapy for ER+ breast cancer. The mechanism for growth control of MBC by high dose estrogen is unclear. We present a patient with metastatic breast cancer whose tumor was found to have amplification of ESR1 by tumor genome sequencing. This patient was treated with high dose estradiol and subsequently experienced a sustained partial response, which was predicted by prior experiments with patient-derived xenograft animal models containing breast cancers with ER amplification.