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Updated ASCO Guidelines for Adjuvant Endocrine Therapy in Breast Cancer

The American Society of Clinical Oncology (ASCO) has released updated guidelines with a focus on adjuvant endocrine therapy in breast cancer for both premenopausal and postmenopausal women.

The majority of breast cancers are considered hormone-positive (HR+)-breast cancer, referring to cancer that is stimulated to grow from exposure to circulating female hormones.

Medications that block the female hormones – either from forming, or from attaching themselves to the cancer cells – are an integral component of therapy for patients with hormone-positive breast cancer.

There are different classes of these medications, called endocrine agents, that work in different ways to block the growth effects of female hormones on breast cancer cells.

Tamoxifen is a type of endocrine agent that is commonly used among pre- or perimenopausal women. Aromatase agents are a large class of endrocine agents that work differently than tamoxifen, and are often used in postmenopausal women.

ASCO has recently updated guidelines for the optimal duration of endocrine treatment for both pre- (which includes peri-) menopausal women and postmenopausal women. This update is based on emerging data including survival and breast cancer recurrence rates.

Premenopausal women with HR+ breast cancer should receive at least 5 years of tamoxifen and should be offered a total duration of 10 years of treatment with tamoxifen.
Postmenopausal women who have received 5 years of tamoxifen should be offered the choice of an additional 5 years of tamoxifen, or a switch to 5 years of aromatase inhibitors.
Postmenopausal women who are treated with tamoxifen for 5 years should be offered an additional 5 years of tamoxifen or subsequent 5 years of an aromatase inhibitor.
Since every patient and cancer is unique, women with breast cancer should speak with their healthcare provider regarding both benefits and side effects for their individual case of each treatment option available.

Reference: Burstein H, Temin S, Anderson H, et al. Adjuvant endocrine therapy for women with hormone receptor-positive breast cancer: American Society of Clinical Oncology Clinical Practice Guideline Focused Update. Journal of Clinical Oncology. 2014; 32(21):2255-2269.