What treatment is recommended for a patient with estrogen receptor (ER) positive breast cancer?

From the Guidelines

Patients with estrogen receptor (ER) positive breast cancer should be treated with endocrine therapy as the cornerstone of treatment, with the standard approach including aromatase inhibitors such as anastrozole (1 mg daily), letrozole (2.5 mg daily), or exemestane (25 mg daily) for postmenopausal women, and tamoxifen (20 mg daily) or ovarian suppression with aromatase inhibitors for premenopausal women. The choice of endocrine therapy should be based on the menopausal status of the patient and the biology of the tumor, with careful attention paid to ovarian production of estrogen 1. For postmenopausal women with metastatic, HR-positive breast cancer, aromatase inhibitors (AIs) should be offered as first-line endocrine therapy (ET) 1.

• Key considerations in the treatment of ER-positive breast cancer include:
  • Menopausal status: premenopausal women should be offered ovarian suppression or ablation in combination with hormone therapy, while postmenopausal women should be offered AIs as first-line ET 1
  • Tumor biology: the choice of endocrine therapy should be based on the biology of the tumor, including the level of ER expression and the presence of other molecular markers 1
  • Prior treatment exposure: the choice of second-line hormonal therapy should take into account prior treatment exposure and response to previous ET 1
  • Patient preferences and tolerance: treatment should be individualized based on patient preferences and tolerance, with careful monitoring of side effects and adjustment of treatment as needed 1

The most recent and highest quality study recommends that postmenopausal women with metastatic, HR-positive breast cancer should be offered AIs as first-line ET, and that premenopausal women should be offered ovarian suppression or ablation in combination with hormone therapy 1. This approach is supported by multiple studies, including the ASCO guideline update and the NCCN guidelines update 1. Overall, the treatment of ER-positive breast cancer should be individualized based on the unique characteristics of the patient and the tumor, with careful consideration of the benefits and risks of different treatment approaches.

From the FDA Drug Label

Available evidence indicates that patients whose tumors are estrogen receptor positive are more likely to benefit from tamoxifen therapy. Tamoxifen citrate tablets are indicated for the treatment of node-positive breast cancer in women following total mastectomy or segmental mastectomy, axillary dissection, and breast irradiation The estrogen and progesterone receptor values may help to predict whether adjuvant tamoxifen therapy is likely to be beneficial. Among women with ER positive or unknown breast cancer and positive nodes who received about 5 years of treatment, overall survival at 10 years was 61.4% for tamoxifen vs. 50.5% for control

Treatment Recommendation:

• Tamoxifen is recommended for patients with estrogen receptor (ER) positive breast cancer.
• The treatment may be beneficial for patients with node-positive or node-negative breast cancer.
• The decision to use tamoxifen should be based on an individual assessment of the benefits and risks of tamoxifen therapy 2, 2.
• The optimal duration of tamoxifen therapy is about 5 years, with proportional reductions in mortality of 26% and breast cancer recurrence of 47% 2.

From the Research

Treatment Options for ER-Positive Breast Cancer

• The treatment for estrogen receptor (ER) positive breast cancer typically involves adjuvant endocrine therapy, which may include tamoxifen or aromatase inhibitors 3.
• For premenopausal women with ER-positive breast cancer, the use of aromatase inhibitors with ovarian suppression has been shown to reduce the risk of breast cancer recurrence compared to tamoxifen alone 4, 5.
• However, the addition of ovarian suppression to aromatase inhibitors or tamoxifen is still a topic of debate, with some studies suggesting that it may not provide significant benefits in terms of overall survival 6.
• The choice of adjuvant endocrine therapy and ovarian suppression may depend on various factors, including the patient's age, menopausal status, and tumor characteristics 7.

Adjuvant Endocrine Therapy Options

• Tamoxifen for 10 years: a common treatment option for premenopausal women with ER-positive breast cancer 3.
• Tamoxifen for 5 years followed by aromatase inhibitors: an alternative treatment option that may be considered for premenopausal women who become postmenopausal during treatment 3.
• Aromatase inhibitors with ovarian suppression: a treatment option that has been shown to reduce the risk of breast cancer recurrence in premenopausal women with ER-positive breast cancer 4, 5.
• Tamoxifen with ovarian suppression: a treatment option that may be considered for premenopausal women with ER-positive breast cancer, although its benefits are still debated 6.

Considerations for Treatment Decisions

• Patient age: younger patients may be more likely to receive ovarian suppression as part of their treatment regimen 7.
• Menopausal status: premenopausal women may require different treatment approaches than postmenopausal women 3, 4.
• Tumor characteristics: the presence of estrogen receptors and other tumor characteristics may influence the choice of adjuvant endocrine therapy 3, 4.