Postmenopausal patient with estrogen receptor–positive, axillary node–negative breast cancer after lumpectomy; which adjuvant therapy is indicated?

• A. Chemotherapy
• B. Tamoxifen
• C. Ovarian ablation
• D. Bisphosphonate therapy

Answer: (B)

Treating estrogen receptor–positive breast cancer after lumpectomy in a postmenopausal woman with node-negative disease centers on blocking estrogen’s ability to stimulate tumor growth. Tamoxifen does exactly that in breast tissue by acting as an estrogen receptor antagonist, reducing the risk of recurrence and improving survival in early-stage ER-positive cancers. In postmenopausal patients like this, endocrine therapy is favored over routine chemotherapy unless there are high-risk features, because it targets the biology of the tumor with a favorable balance of benefits and risks. Ovarian ablation isn’t helpful after menopause since ovarian estrogen production is already minimal. Bisphosphonate therapy helps bone health and may have roles in some settings but is not the primary adjuvant therapy for ER-positive early breast cancer. Thus, tamoxifen is the appropriate choice.