January 10, 2018
by Arturo Loaiza-Bonilla, MD, MSEd
Continuing adjuvant aromatase inhibitor (AI) therapy for 2 years beyond the current standard 5 years of treatment yielded the same level of recurrence prevention as continuing the treatment for an extra 5 years, according to a report at the San Antonio Breast Cancer Symposium.
Women who stopped extension treatment with anastrozole (Arimidex) after 2 years had a 5-year disease-free survival of 71.1%, compared with 70.3% of women who continued the aromatase inhibitor for 5 years (P=0.925). Women who continued the AI for an additional 5 years also had a slightly higher rate of bone fracture (6.3% versus 4.7%, P=0.0553).
The findings came from the ABCSG-16 randomized trial, which involved almost 3,500 postmenopausal women with hormone receptor–positive breast cancer. All the study participants had completed 5 years of adjuvant endocrine therapy and were randomized to extended treatment with the AI for an additional 2 or 5 years.
As oncologists, we are always concerned about the risk of relapse in our hormone receptor-positive early breast cancer patients and typically extend the duration of adjuvant endocrine therapy. These results are practice changing for postmenopausal patients who have already undergone 4 to 6 years of adjuvant endocrine therapy with tamoxifen after surgery and radiation, and now can consider two additional years of extended aromatase inhibitor therapy, in this case anastrozole, in order to prevent relapse.
Loiaza-Bonilla is affiliated with Cancer Treatment Centers of America.