Fulvestrant (Faslodex) for Hormone-Positive Stage 4 Breast Cancer

Fulvestrant, marketed as Faslodex, is injected into the buttock for metastatic hormone-positive breast cancer.

How Does Fulvestrant Work?

Fulvestrant prevents estrogen from binding to breast cancer cell receptors. In estrogen-receptor-positive (ER+) disease, estrogen binds these receptors and sends cancer cells growth and division signals . Fulvestrant blocks this, suppressing cell growth and proliferation.

When Is Fulvestrant Used?

It slows breast cancer progression and spread and reduces disease-related symptoms.

It treats postmenopausal patients with locally advanced or metastatic hormone-positive disease that worsened during previous hormonal treatments as the eligible group.

Administration and Dose

Fulvestrant 500 mg, two injections of 250 mg each per package, is injected into buttock muscle: intramuscular (İ.M.) administration. Initial doses on days 1, 14 and 28 are followed every 28 days.

It is generally administered in day-treatment units and continued until follow-up imaging, such as CT, PET-CT or ultrasound, shows progression and loss of efficacy.

Side Effects

Each medicine in a combination has its own effects. Combined side effects are estimated from clinical trials have been estimated from the results. The frequency of side effects may sometimes fall within a range (for example, hot flashes at % 8-13). This is because the results obtained from clinical studies differ.

The most common effects in trials were:

• Bone pain(14%) 
• Nausea (11%) 
• Joint pain (10-19%)
• Constipation (10%)
• Vomiting (9%)
• Shortness of breath (9%)
• Hot flashes (8-13%) 
• Injection-site pain / allergy (6-14%)
• Sweating (4%)
• Urinary infection (2-4%)
• Weight loss (1%)

An average % 2 - 3 stopped fulvestrant because of intolerable effects in trials.

Follow-Up

How Often Is Follow-Up Needed?

We recommend monthly blood tests in metastatic patients: complete blood count and comprehensive metabolic panel.

How Often Is Imaging Needed?

As in other stage 4 cancers, imaging occurs before treatment and at oncologist-recommended intervals, usually every 2 or 3 months. Methods include bone scans, MRI, CT or PET-CTas appropriate.

How Do Blood Tests or Imaging Affect Treatment?

Depending on results, your doctor may continue fulvestrant, adjust dose or change treatment.

Points to Consider

• Only limited fluid can be given in one intramuscular (I.M.) injection, so the total dose requires two same-day injections, one per buttock, each slowly over 1-2 minutes. 
• Your oncology pharmacist should check medicine interactions.

Individual Drug Label Information

Fulvestrant (Faslodex)

• Mechanism: A new-generation estrogen-receptor antagonist approved by the FDA in 2002. Besides preventing estrogen binding and intracellular growth signals, trials show it reduces surface estrogen and progesterone receptor numbers.
• Fulvestrant is an intramuscular (İM) injection.
• Liver function may require dose adjustment.
• Only postmenopausal women should receive it.

General Fulvestrant (Faslodex) Side Effects

• Hot flashes are among the commonest. Discuss ways to minimize and treat them. Do not use medicines, medicinal herbs or natural supplements without consulting your doctor or pharmacist.
• Injection-site pain
• Headache
• Bone and joint pain
• Loss of strength
• Nausea/Vomiting
• Constipation or diarrhea 
• Weakness 
• Rapid breathing

Related Topic

Evidence-Based Complementary Medicine to Reduce Breast Cancer and Treatment Side Effects