Addition of First-Line Fulvestrant to Anastrozole in Metastatic Breast Cancer
Posted: Tuesday, April 23, 2019
The long-term survival rates of postmenopausal patients with metastatic breast cancer are improved by the addition of fulvestrant to anastrozole, the phase III SWOG S0226 trial found. The benefit seemed to be more prominent in women who had not previously been exposed to adjuvant endocrine therapy.
The open-label trial tested whether a combination of anastrozole and fulvestrant was more effective than anastrozole alone for treating postmenopausal women with metastatic breast cancer. Researchers found that the drug combination was associated with increased long-term survival, compared with anastrozole alone, “despite substantial crossover to fulvestrant after [disease] progression during therapy with anastrozole alone.”
The study involved 694 eligible patients: 349 were treated with the combination therapy and 345 were treated with anastrozole alone. The combination group was given 500 mg of fulvestrant on the first day; 250 mg on days 14 and 28; and the same dose again every 28 days, in addition to standard doses of anastrozole. According to The New England Journal of Medicine, in which the results were published, 40% of patients had previously received adjuvant tamoxifen.
The median follow-up was 7 years among those who did not have disease progression; maximum follow-up was 12 years. The results showed that the combination-therapy group had 247 deaths among 349 women (71%) and a median overall survival of 49.8 months, as compared with 261 deaths among 345 women (76%) and a median overall survival of 42.0 months in the anastrozole-alone group. In women who had not previously received tamoxifen, the improvement in overall survival was more prominent than in those who had not received prior tamoxifen treatment.
Disclosure: The study was funded by the National Cancer Institute and AstraZeneca. The study authors’ full disclosures may be found at nejm.org.