SABCS: Serum Hormones Can Help ID Benefit of Anastrozole

MONDAY, Dec. 11, 2023 (HealthDay News) -- Serum hormone concentrations can help ascertain which women with breast cancer will benefit from anastrozole treatment, according to a study published online Dec. 6 in The Lancet Oncology to coincide with the annual San Antonio Breast Cancer Symposium, held from Dec. 5 to 9 in San Antonio.

Jack Cuzick, Ph.D., from Queen Mary University of London, and colleagues conducted a case-control study using data from the IBIS-II prevention trial involving postmenopausal women aged 40 to 70 years at high risk for breast cancer. Women were randomly assigned to receive anastrozole (1 mg/day, orally) or placebo daily for five years (1,920 and 1,944 women, respectively). In this preplanned study, the primary analysis was the impact of the baseline estradiol-to-sex hormone binding globulin (SHBG) ratio on development of all breast cancers.

Participants were followed for a median of 131 months, during which time there were 85 and 165 cases of breast cancer (4.4 and 8.5 percent) in the anastrozole and placebo groups, respectively. The researchers identified a trend of increasing breast cancer risk with increasing estradiol-SHBG ratio in the placebo group, but not in the anastrozole group. In the placebo group, but not in the anastrozole group, there was also a weaker effect observed for the testosterone-SHBG ratio. In quartiles 2, 3, and 4, but not 1, of the estradiol-SHBG ratio, a relative benefit of anastrozole was seen.

"Measuring serum hormone concentrations could be an inexpensive method to help clinicians differentiate which women will benefit most from use of aromatase inhibitor for the prevention of breast cancer," the authors write.

Several authors disclosed ties to the pharmaceutical industry.

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