Guidelines for the use of hormone therapy in hormone receptor-positive patients with metastatic breast cancer.

This report aimed to develop recommendations for endocrine therapy in women with hormone receptor-positive metastatic breast cancer.

Endocrine therapy, also known as hormone therapy (HT) is used to treat hormone receptor (HR) positive metastatic breast cancer (MBC). HR positive MBC depends on the hormones estrogen or progesterone for growth. Endocrine therapy works to block or decrease the production of these hormones to treat the cancer.

Hormone therapies are commonly used in patients with early-stage breast cancer. The American Society of Clinical Oncology (ASCO) has published these new guidelines to help doctors and patients make decisions on HT for more advanced breast cancers.

The ASCO formed a panel to review all information from 2008 to 2015 and used the information to create recommendations. Information reviewed included the sequencing of HT and the treatment of women dependent on menopausal status.

 Patients who have tumors with any level of hormone receptors should be offered HT as a treatment option. HT should be continued until there is definite disease progression.

It is recommended that HT alone or in combination should be used as an initial treatment in all cases, except in patients with life threatening disease. Results comparing single HTs with combined HTs have been mixed. It is recommended that chemotherapy follow HT, rather than being combined. Combining the two treatments did not lead to improved time to disease progression.

It is recommended that the type of HT should depend on menopausal status. Premenopausal women should be treated with ovarian suppression or ablation in combination with HT. Fertility should be discussed with premenopausal women before treatment.

It is recommended that postmenopausal women be treated with aromatase inhibitors (AI, a type of HT) such as letrozole (Femara) with or without palbociclib (Ibrance) as a first line therapy. Palbociclib is a therapy that targets certain proteins that are involved with cancer growth. Postmenopausal women should be treated with fulvestrant (Faslodex, an HT), with or without palbociclib as a second line therapy.

Postmenopausal women who progress on AI may be treated with everolimus (Afinitor, blocks a protein involved in cancer growth) and exemestane (Aromasin, an AI).

These guidelines set out recommendations about endocrine therapy for women with HR positive MBC.