In a Japanese phase III trial (AERAS) reported in the Journal of Clinical Oncology, Iwase et al found that an additional 5 years of adjuvant anastrozole after 5 years of anastrozole or tamoxifen followed by anastrozole was associated with improved disease-free survival vs no further anastrozole treatment among postmenopausal patients with hormone receptor–positive breast cancer.
In the multicenter open-label trial, 1,593 patients with available follow-up who were disease-free after 5 years of anastrozole or 2 to 3 years of tamoxifen followed by 2 to 3 years of anastrozole were randomly assigned between November 2007 and November 2012 to continue anastrozole for 5 years (continue group, n = 787) or stop anastrozole (stop group, n = 806). The primary endpoint was disease-free survival, including breast cancer recurrence, second primary cancers, and death from any cause.
Disease-free survival at 5 years was 91% (95% confidence interval [CI] = 89%–93%) in the continue group vs 86% (95% CI = 83%–88%) in the stop group (hazard ratio [HR] = 0.61, 95% CI = 0.46%–0.82%, P < .0010).
Extended anastrozole treatment was associated with reduced incidence of local recurrence (n = 10 [1.3%] vs n = 27 [3.3%]) and second primary cancers (n = 27 [3.4%] vs n = 52 [6.5%], P = .0074). Distant recurrence occurred in 41 (5.2%) vs 61 (7.6%) patients (HR = 0.68, 95% CI = 0.46–1.01, P = .0553).
Death occurred in 21 (2.7%) vs 19 (2.4%) patients (HR for overall survival = 1.13, 95% CI = 0.61–2.10, P = .7042).
Any-grade arthralgia (37% vs 29%), new-onset osteoporosis (47% vs 44%), stiff joints (21% vs 12%), and hot flashes (14% vs 10%) were more common in the continue group. No significant difference in bone fracture was observed between groups (10% vs 9%). The incidence of grade ≥ 3 adverse events was less than 1% in both groups.
The investigators concluded, “Continuing adjuvant anastrozole for an additional 5 years after 5 years of initial treatment with anastrozole or tamoxifen followed by anastrozole was well tolerated and improved disease-free survival. Although no difference in overall survival was observed as in other trials, extended anastrozole therapy could be one treatment choice in postmenopausal patients with [hormone receptor–]positive breast cancer.”
Takuji Iwase, MD, of the Department of Breast and Endocrine Surgery, Japanese Red Cross Aichi Medical Center Nagoya Daiichi Hospital, Nagoya, is the corresponding author for the Journal of Clinical Oncology article.
Disclosure: The study was supported by the Comprehensive Support Project for Oncology Research of the Public Health Research Foundation, Japan. For full disclosures of the study authors, visit ascopubs.org.
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