What is the role of hormone therapy in the treatment of metastatic breast cancer?

Updated: Dec 27, 2019
  • Author: Pavani Chalasani, MD, MPH; Chief Editor: John V Kiluk, MD, FACS  more...
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Answer

For patients who have hormone receptor (ER and/or PR)–positive disease without a life-threatening component (eg, massive liver metastases) or systemic symptoms requiring immediate palliation for comfort, in general, hormone manipulation is the initial treatment of choice. Response rates are higher with chemotherapy, but so is the incidence of potentially dangerous toxicity, and there is no evidence that patients live longer as a result of receiving initial chemotherapy.

For ER–positive metastatic breast cancer, the American Society of Clinical Oncology (ASCO) recommends using endocrine therapy rather than chemotherapy as first-line treatment, except in patients with immediately life-threatening disease or if there are concerns about endocrine resistance. The recommendation is part of an ASCO clinical practice guideline on the use of chemotherapy and targeted therapy for women with human epidermal growth factor 2 (HER2)-negative (or unknown) advanced breast cancer, with recommendations based on a systematic review of 79 studies. [141]

A trial of hormone manipulation alone can assess whether hormone therapy is effective, which is impossible to determine if it is given together with cytotoxic chemotherapy. This is especially important when the patient has relapsed disease, because the benefit of second-line hormone manipulation is nearly 50%, and failure to benefit from an initial trial with endocrine therapy correlates with second-line failure. Common hormone therapies and dosages are listed in Table 5, below.

Table 5. Hormone Agents Used in Breast Cancer (Open Table in a new window)

Agent

Dose and Schedule

Postmenopausal

Tamoxifen

20 mg PO every day

Or

Aromatase inhibitor

Anastrozole

1 mg PO every day

Letrozole

2.5 mg PO every day

Exemestane

25 mg PO every day

Or

Fulvestrant

500 mg IM on days 1, 15, 29, and once monthly thereafter

Or

Megestrol

40 mg PO 4 times a day

Premenopausal

Tamoxifen

20 mg PO every day

Or

Aromatase inhibitor + LHRH*

Leuprolide

7.5 mg IM depot q28d

22.5 mg IM q3mo

30 mg IM q4mo

Goserelin

3.6 mg SC depot q28d

10.8 mg SC q3mo

Megestrol

40 mg PO 4 times a day

*LHRH = luteinizing hormone–releasing hormone.

 

In a randomized study, Mehta et al found that combination treatment with anastrozole and fulvestrant was superior to either anastrozole alone or sequential anastrozole and fulvestrant treatment in patients with hormone-receptor-positive metastatic breast cancer. [142]

In the international, double-blind phase III MONARCH 2 trial, 669 patients were randomized in a 2:1 ratio to abemaciclib (a CDK inhibitor) plus fulvestrant or fulvestrant plus placebo. Patients received 500 mg of fulvestrant plus placebo or 150 mg of abemaciclib twice daily. The median progression-free survival was 16.4 months in the abemaciclib arm versus 9.3 months in the fulvestrant-alone group. The overall response rates among patients with measurable disease were 48.1% and 21.3% in the abemaciclib and control arms, respectively. [143]


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