According to an article recently published in the Lancet Oncology, women with breast cancer who switch from tamoxifen (Nolvadex®) to Aromasin® (exemestane) have an increased risk of bone fractures. However, it was also noted that overall survival is improved with Aromasin.
The majority of breast cancers are referred to as hormone-positive breast cancer. These cancers are stimulated to grow by the circulating female hormones estrogen and/or progesterone. Women with hormone-positive breast cancer are often treated with hormone therapy, an approach in which estrogen and progesterone are either suppressed or blocked from entering cancer cells.
Historically, tamoxifen was the main agent used as hormone therapy for breast cancer patients. More recently, aromatase inhibitors have demonstrated improved outcomes compared to tamoxifen. Researchers continue to assess side effects associated with aromatase inhibitors in order to reduce or prevent these complications altogether.
Researchers affiliated with the Intergroup Exemestane Study (IES) recently conducted a subgroup analysis on the effects of Aromasin on bone health of women with breast cancer. The IES was a large trial that included postmenopausal women with early, hormone-positive breast cancer who were initially treated with tamoxifen. One group of patients in this trial continued therapy with tamoxifen, while the other switched to Aromasin. Overall, women who switched to Aromasin had improved survival compared to women who remained on tamoxifen. The subgroup analysis from the IES trial regarding bone health revealed the following outcomes:
- Bone mineral density was lowered by 2.7% in the lumbar spine and 1.4% in the hip among patients who switched to Aromasin.
- At 58 months follow-up, 7% of patients who switched to Aromasin had developed bone fractures compared with 5% who continued to stay on tamoxifen.
- No patients with normal bone mineral density at the initiation of the trial developed osteoporosis.
The researchers concluded that postmenopausal women with hormone-positive breast cancer who switch from tamoxifen to Aromasin have reduced bone mineral density and increased bone fractures compared to women who continue treatment with tamoxifen. However, previous findings from this trial have demonstrated that overall survival is improved among patients who switch to Aromasin.
Patients who switch to aromatase inhibitors such as Aromasin may wish to speak with their physician regarding their treatment options and potential effects on bone health.
Reference: Coleman R, Banks L, Girgis S, et al. Skeletal effects of exemestane on bone mineral density, bone biomarkers, and fracture incidence in postmenopausal women with early breast cancer participating in the intergroup exemestane study (IES): a randomised controlled study. Lancet Oncology [early online publication]. January 24, 2007. DOI: 10.1016/S1470-2045(07)70003-7.
Related News: Switching to Aromasin® Improves Survival Among Postmenopausal Women with Early Breast Cancer (06/13/2006)
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