Adjuvant endocrine therapy should be extended from 5 to 10 years in women with hormone receptor–positive breast cancer, according to an updated clinical practice guideline published online May 27 in the Journal of Clinical Oncology.
"For decades, tamoxifen taken for 5 years was the standard adjuvant endocrine treatment. More recently, patients who are postmenopausal also have been offered the option of taking an aromatase inhibitor (AI) as an alternative to tamoxifen or in sequence after tamoxifen," said Dr. Harold J. Burstein, cochair of the American Society of Clinical Oncology expert panel that wrote the update.
However, since the last update (2010) of this clinical practice guideline, emerging research from international randomized trials has demonstrated that women who continue adjuvant endocrine therapy for an additional 5 years have a modest gain in overall survival, as well as lower rates of recurrence and contralateral breast cancer, the panel noted.
Now, pre- and perimenopausal women diagnosed with hormone receptor–positive breast cancer should be offered a total of 10 years of adjuvant endocrine therapy. Which agents they should take depends on their menopausal status. Pre- and perimenopausal women can be given tamoxifen but not aromatase inhibitors; postmenopausal women can be given either agent, but the total duration of aromatase inhibitors shouldn’t exceed 5 years, Dr. Burstein and his associates said (J. Clin. Oncol. 2014 May 27 [doi:10.1200/JCO.2013.54.2258]).
"It is not known which strategy is preferred; tamoxifen and AIs have different adverse effect profiles that might reasonably inform that choice, and patient preferences based on the tolerability of these agents in individual women should be considered," the guideline states.
The known adverse effects of both treatments, which include menopausal symptoms and rare cases of endometrial cancer and thromboembolism, persist with longer duration of treatment. But no new adverse effects specific to that increased duration have been identified to date, Dr. Burstein and his associates said.
Given the importance of adjuvant endocrine therapy to patient survival and quality of life, "clinicians are encouraged to inquire diligently about treatment compliance and treatment-related adverse effects, and to pursue interventions known to mitigate adverse effects and enhance adherence," the guideline says.
The updated recommendations, along with other explanatory information, can be obtained at www.asco.org/guidelines/endocrinebreast. Patient information is available at www.cancer.net.