From Reuters Health Information
Aromatase Inhibitor Efficacy Falls as BMI Rises in Young Breast Cancer Patients
NEW YORK (Reuters Health) May 12 - In premenopausal women taking adjuvant anastrozole for breast cancer, body mass index (BMI) has a significant impact on outcomes, an Austrian study shows.
Overweight women in the anastrozole group had higher risks for disease recurrence and death, in a retrospective analysis of data from an earlier trial.
"Clearly, these results should currently be viewed as hypothesis generating because of the retrospective nature of our analyses," the research team advises. "In current clinical practice, however, physicians may want to include this aspect in the risk-benefit assessment in counseling overweight premenopausal patients with breast cancer about their choice of adjuvant endocrine treatment."
The use of aromatase inhibitors in premenopausal women, combined with ovarian suppression, is "attractive in principle," according to researcher Dr. Michael Gnant, at the Medical University of Vienna, and colleagues.
As they wrote in their paper, however, they suspected that "BMI as a surrogate parameter for total body aromatization impacts on the efficacy of aromatase inhibitors."
They examined this question, in a study reported online May 9th in the Journal of Clinical Oncology, using data from the ABCSG-12 trial, which compared goserelin in combination with tamoxifen versus anastrozole in premenopausal patients with endocrine-responsive breast cancer.
Overall, there was a trend for worse disease-free survival in the 573 overweight women in the study compared with the 1111 normal-weight patients, with a disease-recurrence hazard ratio of 1.24 (p=0.15).
The trend for overall survival was similar, with a mortality HR of 1.49 (p=0.10), according to the report.
On further analysis, it was apparent that this trend was driven by the anastrozole group, since BMI wasn't a factor in women treated with tamoxifen.
In the anastrozole group, the risk of disease recurrence was 15.1% in overweight women compared with 9.0% in normal weight women (p=0.02). This translates to a hazard ratio of 1.60, the authors found.
Furthermore, in the anastrozole arm, overweight patients had more than double the risk of death compared with normal weight patients who (HR 2.14, p=0.01).
"BMI significantly impacts on the efficacy of anastrozole plus goserelin in premenopausal patients with breast cancer, probably through influencing aromatase availability and/or ovarian suppression by goserelin," the authors conclude.
SOURCE: http://bit.ly/l9sX8u J Clin Oncol 2011.