After the IBIS-II presentation at the San Antonio Breast Cancer Symposium, Carlos L. Arteaga, MD, of Vanderbilt Ingram Cancer Center, Nashville, noted that women at high risk are afraid of developing breast cancer and that pharmacologic intervention may allay their anxiety.
“Dr. Cuzick’s study with more than 4,000 women shows that anastrozole has an impact on the development of breast cancer. His data showed that side effects are not terribly different in the anastrozole arm than in the placebo arm. He suggested that the bad rap of joint pain and arthralgias may not be due to the aromatase inhibitor itself.”
In an accompanying editorial in The Lancet,1 David Cameron, MD, MRCP, Edinburgh Cancer Centre, Western General Hospital, Edinburgh, was less enthusiastic about the widespread use of anastrozole for prevention of breast cancer. In his view, no study of pharmacoprevention of breast cancer, including IBIS-II, has demonstrated a reduction in mortality.
“For any woman considering 5 years’ anti-oestrogen therapy to reduce her risk of breast cancer without evidence to suggest that she will have a longer life, the perceived and actual toxicity of this intervention becomes important,” he wrote. “The financial costs of breast cancer prevention might have decreased, but the toxicity cost to women has not.”
Dr. Cameron noted that compliance is an obstacle to chemoprevention, and that about 100 to 200 additional women had musculoskeletal and vasomotor events in the anastrozole group, “often to a moderate or severe level—to prevent 15 symptomatically diagnosed breast cancers.”
Dr. Cameron wrote that newer drugs are needed to reduce breast cancer mortality, with an improved safety profile, and that better ways are needed to target the drugs to women who will derive the greatest benefit. ■
Disclosure: Dr. Arteaga and Cameron reported no potential conflicts of interest.
1. Cameron DA: Breast cancer chemoprevention: Little progress in practice. Lancet. December 12, 2013 (early release online).
Five years of treatment with anastrozole reduced the risk of breast cancer by 53% in postmenopausal women at high risk for developing the disease, according to an analysis of the International Breast Cancer Intervention Study (IBIS)-II trial. Anastrozole reduced the risk of estrogen...
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