Fulvestrant: Hormone Therapy par Excellence

Current endocrine or hormonal treatment options include selective estrogen receptor modulators (tamoxifen), aromatase inhibitors and negative regulators of estrogen receptor expression, such as fulvestrant. We'll see in the article how the latter works.
Fulvestrant: Hormone Therapy par Excellence

Last update: 04 October, 2021

Hormone therapy is a great option for many issues. Fulvestrant is a drug that blocks estrogen receptors, one of the female sex hormones. Doctors use it to treat some types of breast cancer that use estrogen to grow and multiply in the body. We know that most breast neoplasms are dependent on estrogenic stimuli, hence the blockade of these hormones is the main therapeutic strategy.

Recently, the use of targeted therapies together with hormone therapy has improved the results of advanced disease-free survival, with fewer side effects than those produced by conventional chemotherapy.

Hormone-dependent or HR+ breast cancer

breast pain

Breast cancer is the most frequently diagnosed type of neoplastic disease and the leading cause of mortality in women. Several studies have shown that most of these tumors are estrogen and/or progesterone receptor-positive.

Hormone receptor-positive disease is also called RH+ breast cancer. Its behavior is different from that of hormone receptor-negative or HR- neoplasms. They differ mainly in terms of the course of the disease as well as in the timing and type of recurrence.

Patients with HR+ tumors experience a constant lifetime risk of late recurrence as well as cancer-related death.

Current treatment of breast cancer in hormone-dependent tumors

Currently, the preferred option for the treatment of hormone-receptor-positive breast cancer is hormone therapy, even if metastases are present. The menopausal status of the patient, among other factors, determine the hormone treatment:

  • Postmenopausal women: Can use most available therapies.
  • Premenopausal women: Only tamoxifen is available. If these patients require the use of other treatments such as fulvestrant or aromatase inhibitors, ovarian function suppression is necessary.

Current endocrine or hormonal treatment options include selective estrogen receptor modulators (tamoxifen), aromatase inhibitors, and negative regulators of estrogen receptor expression such as fulvestrant.

In addition to menopausal status, the choice of treatment type will also depend on the use of and response to previous therapies, disease-free time, expected toxicity, and tumor makeup.

Breast cancer diagram treated with hormone therapy

The efficacy of fulvestrant was first demonstrated in the FIRST study in which it was shown that an endocrine therapy could be more effective than an aromatase inhibitor in the first line of breast cancer treatment.

Another study, known as FALCON 3, also compared an aromatase inhibitor and fulvestrant in breast cancer patients with non-visceral metastatic disease. Fulvestrant showed a significant benefit in progression-free survival, thus reinforcing its efficacy.

Specialists have conducted other studies that support the administration of fulvestrant with CDK 4/6 inhibitor drugs, such as palbociclib. The PALOMA 3 study demonstrated that palbociclib is associated with significant benefit in patients previously treated with HR+ breast cancer.

Mechanism of action of fulvestrant in the body

As we’ve explained, fulvestrant is an effective drug for the treatment of breast tumors that have estrogen receptors. When tumor growth is stimulated by the effect of estrogen binding to the cancer receptors, then doctors indicate this therapy.

Fulvestrant is an estrogen receptor antagonist drug. This means that it interacts with the receptor at the same place where the estrogen molecules do. Therefore, it owes its efficacy to its ability to bind, block and degrade estrogen receptors.


Although we’ve made great strides in the fight against cancer, there are still many doors open and much research remains to be done.

The development of fulvestrant was undoubtedly a great advance in the treatment of this disease. Researchers continue to investigate its potential in association with palbociclib.

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