Fast Five Quiz: Key Aspects of Metastatic Breast Cancer

Elwyn C. Cabebe, MD


December 02, 2021

Treatment with a single endocrine agent or an approved CDK4/6 inhibitor in combination with an endocrine agent is usually continued in patients with metastatic, hormone-responsive breast cancer until disease progression. Considerations are as follows:

  • AIs have been shown to be more effective than tamoxifen for adjuvant therapy and metastatic disease.

  • Postmenopausal women who experience relapse or develop progressive disease on a selective estrogen receptor modulator (eg, tamoxifen) may be switched to an AI.

  • Patients who experience relapse or develop progression of disease while receiving a nonsteroidal AI (eg, anastrozole or letrozole) may be switched to a steroidal AI (eg, exemestane) or a selective estrogen receptor downregulator (eg, fulvestrant).

  • A nonsteroidal AI and a CDK4/6 inhibitor should be offered to postmenopausal patients (and to premenopausal patients combined with chemical ovarian function suppression) with treatment-naive hormone receptor–positive metastatic breast cancer.

  • Fulvestrant and a CDK4/6 inhibitor should be offered to patients with progressive disease during treatment with AIs (or who develop recurrence within 1 year of adjuvant AI therapy) with or without one line of prior chemotherapy for metastatic disease, or as first-line therapy. Treatment should be limited to those without prior exposure to CDK4/6 inhibitors in the metastatic setting.

  • The fulvestrant regimen when administered as monotherapy is 500 mg intramuscularly on days 1, 15, and 29 and once monthly thereafter; it may also be combined with a CDK 4/6 inhibitor, such as abemaciclib, palbociclib, or ribociclib.

  • Optionally, consider the androgenic agent fluoxymesterone (10 mg orally twice daily) or the progestational agent megestrol acetate (40 mg orally four times daily) or estradiol (2 mg orally twice daily).

  • Systemic chemotherapy should be reserved for patients with hormone-insensitive disease or those with symptomatic hormone-sensitive disease who have not responded to any hormone therapy options or who are moderately to severely symptomatic and in urgent need of symptom palliation.

  • The options for cytotoxic-containing chemotherapy include single-agent therapy and combination cytotoxic regimens.

Learn more about endocrine regimens that may be offered as first-line therapy for postmenopausal women with metastatic breast cancer.


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