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ASCO: Tamoxifen may be used up to 10 years for non-metastatic, HR-positive breast cancer
ASCO today issued updated recommendations on the use of tamoxifen for women with non-metastatic, ER-/PR-positive breast cancer.
The guideline — last updated in 2010 — suggests women who are diagnosed with hormone-receptor–positive disease when premenopausal may continue treatment with tamoxifen for 10 years. If women are postmenopausal after 5 years, they may continue tamoxifen, or receive treatment with an aromatase inhibitor, for a total endocrine therapy treatment duration of 10 years.
Women who are postmenopausal at the time of diagnosis should be offered one of four options: 10 years of tamoxifen; 5 years of an aromatase inhibitor; 5 years of tamoxifen followed by up to 5 years of an aromatase inhibitor; or 2 to 3 years of tamoxifen followed by an aromatase inhibitor for up to 5 years.
Harold J. Burstein
“Tamoxifen taken for 5 years has been the standard adjuvant endocrine treatment for decades, but we now have evidence to recommend up to 10 years of tamoxifen for women with hormone receptor-positive breast cancer,” Harold J. Burstein, MD, PhD, co-chair of ASCO’s Expert Panel that wrote the guideline update, said in a press release. "Postmenopausal women also have the option of taking an aromatase inhibitor as an alternative to tamoxifen or in sequence after tamoxifen. Aromatase inhibitors are not recommended for premenopausal women.”
In addition, the guidelines recommend use of the alternative endocrine therapy for women who are intolerant of the other. If these women discontinued an aromatase inhibitor before 5 years, they may receive tamoxifen for a total of 5 years. If they received tamoxifen for 2 to 3 years, they may receive an additional 5 years of an aromatase inhibitor.
The updated guidelines were based on the results of five studies reviewed since 2010. The two studies with the largest populations and longest follow-up demonstrated 10 years of tamoxifen was superior to 5 years.
Data from one of those studies — the Adjuvant Tamoxifen Longer Against Shorter (ATLAS) trial — indicated 10 years of tamoxifen was associated with a 2.8% reduction in breast cancer-specific mortality. The recurrence rate risk ratio was 21.4% for 10 or more years of treatment compared with 25.1% for 5 to 9 years of treatment. The risk for contralateral disease was 12% lower with tamoxifen.
The ASCO guideline also emphasizes the role of physician–patient conversations when discussing extended adjuvant endocrine therapy.
“It is important for clinicians and patients to discuss the trade-offs between potential risks of side effects and potential benefits of taking adjuvant endocrine therapy for up to 10 years,” Jennifer Griggs, MD, MPH, co-chair of the ASCO Expert Panel, said in the press release. “Many women taking adjuvant tamoxifen experience side effects, and these appear to persist with longer duration. However, the trials did not find any new or unexpected side effects.”
Disclosure: The researchers report consultant/advisory roles with and honoraria or research funding from AbbVie, AstraZeneca, Celgene, MedImmune, Merck, Novartis and Pfizer.
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