Treatment Options for Hormone Receptor-Positive Breast Cancer
For hormone receptor-positive breast cancer, endocrine therapy is the preferred initial treatment option, except in cases of visceral crisis or proven endocrine resistance. 1
First-Line Endocrine Therapy Options
- For postmenopausal patients with hormone receptor-positive metastatic breast cancer, aromatase inhibitors should be offered as first-line endocrine therapy 1
- The choice of first-line endocrine therapy depends on type and duration of adjuvant therapy as well as time elapsed since completion of adjuvant therapy 1
- For premenopausal women, ovarian suppression or ablation in combination with hormonal therapy is recommended, with either GnRH agonists or oophorectomy achieving similar results 1
- For patients with HR-positive/HER2-positive disease, HER2-targeted therapy combined with chemotherapy has demonstrated improvement in overall survival and is the preferred first-line approach in most cases 1, 2
Combination Approaches with CDK4/6 Inhibitors
- The addition of CDK4/6 inhibitor palbociclib to an aromatase inhibitor as first-line therapy for postmenopausal patients provides significant improvement in progression-free survival with acceptable toxicity 1
- Fulvestrant and a CDK4/6 inhibitor should be offered to patients with progressive disease during treatment with aromatase inhibitors or who develop recurrence within 1 year of adjuvant AI therapy 1
- For pre/peri/postmenopausal patients beyond first-line therapy, adding CDK4/6 inhibitor palbociclib to fulvestrant provides significant improvement in progression-free survival 1
Sequential Therapy Approach
- Sequential hormonal therapy should be offered to patients with endocrine-responsive disease 1
- The choice of second-line hormonal therapy should take into account prior treatment exposure and response to previous endocrine therapy 1
- After second-line endocrine therapy, little high-level evidence exists to help select the optimal sequence of endocrine therapy 1
Special Considerations for HR+/HER2+ Disease
- For HR+/HER2+ metastatic breast cancer, HER2-targeted therapy combined with chemotherapy is the preferred first-line approach as it has demonstrated overall survival benefits 2
- The addition of HER2-targeted therapy to first-line aromatase inhibitors should be considered for patients with HR+/HER2+ disease in whom chemotherapy is not immediately indicated 1, 2
- For patients who have completed chemotherapy, continuing HER2-targeted therapy with the addition of endocrine therapy is a reasonable approach 2
Treatment Duration and Monitoring
- Treatment should be continued until there is unequivocal evidence of disease progression documented by imaging, clinical examination, or disease-related symptoms 1
- Tumor markers or circulating tumor cells should not be used as the sole criteria for determining progression 1
- Regular monitoring of treatment response is recommended after 3 months of endocrine therapy by clinical evaluation, subjective symptom evaluation, blood tests, and repeating initially abnormal radiologic examinations 1
Important Caveats and Pitfalls
- Combined endocrine therapy and chemotherapy is not recommended 1, 3
- Endocrine therapy may be active in patients with negative ER and PR determinations, especially in soft tissue disease and/or bone-dominant disease, as false-negative determinations of hormone receptor status are not uncommon 1
- Avoid using endocrine therapy alone in HR+/HER2+ metastatic breast cancer patients, as progression-free survival is significantly shorter compared to combination approaches 2
- When using HER2-targeted therapy plus endocrine therapy without chemotherapy, careful patient selection is crucial, as this approach is not appropriate for patients with aggressive or symptomatic disease 2
By following these evidence-based recommendations, clinicians can optimize treatment outcomes for patients with hormone receptor-positive breast cancer, improving both progression-free survival and quality of life.