Join William Gradishar, MD and Seema Khan, MD as they present their multidisciplinary expertise on a range of cases pertaining to hormone sensitive breast cancer.

The mainstay of the treatment of hormone receptor-positive breast cancer is endocrine therapy regardless of age, lymph node status and whether or not adjuvant chemotherapy is given. Ongoing issues in the treatment of hormone receptor positive disease are duration of therapy in the adjuvant setting and the choice of therapy in the metastatic setting.  In addition, for postmenopausal women the treatment algorithm is more complex and several different adjuvant strategies have been studied: treatment with aromatase inhibitors (AI) for 5 years; the sequential strategy, starting with tamoxifen and switching to an AI early (after 2–3 years) or late (after 5 years); or treatment with tamoxifen for 5 years in women who have contraindications to AI. Therefore, selecting the most efficient treatment strategy based on patient characteristics and adverse effects can be challenging.

Although endocrine therapy is the cornerstone of treatment of hormone positive advanced breast cancer, development of resistance to therapy and disease progression is frequently reported.  The results of the BOLERO-2 trial has led to optimism that endocrine resistance might be overcome with the addition of an mTOR inhibitor to endocrine therapy, especially in previously treated patients.

For HER2 positive disease, newer agents are being explored. Pertuzumab binds to different epitopes of HER2 receptor compared to trastuzumab and these two drugs have complementary mechanisms of action. Pertuzumab in combination with trastuzumab and a taxane was recently included in the NCCN Guidelines for Breast Cancer as a preferred first-line option for human epidermal growth factor receptor 2 (HER2)-positive recurrent or metastatic breast cancer that is hormone receptor-negative or hormone receptor-positive and endocrine therapy refractory. T-DMI is another newer anti-HER2 therapy under investigation for advanced HER2 positive tumors with promising preliminary results.

Clinicians use individual patient characteristics, adverse event profiles of regimens, and patient preference to select the most effective and tolerable treatment strategy for the individual. In patients with breast cancer, treatment decisions are also made based on marker status, menopausal status, and stage of the disease. The impact of advances in diagnostics, surgery, and drug or radiation therapies are lost if those advances are not provided appropriately to patients as defined by the evidence.