Lasofoxifene is attractive option for breast cancer prevention
MedWire News: The selective estrogen-receptor (ER) modulator lasofoxifene appears to reduce the risks for both total, and ER-positive invasive breast cancer in postmenopausal women with osteoporosis, the results of a randomized-controlled trial show.
The risk reduction was greatest among women with high estradiol levels, report Andrea LaCroix (Fred Hutchinson Cancer Research Center, Seattle, Washington, USA) and colleagues in the Journal of the National Cancer Institute.
As part of the Postmenopausal Evaluation and Risk-Reduction with Lasofoxifene (PEARL) trial, LaCroix and team evaluated the effect of the drug on the risk for total and ER-positive breast cancer.
In total, 8556 postmenopausal women (mean age 67 years) with osteoporosis and normal mammograms were randomly assigned to receive either lasofoxifene 0.25 or 0.5 mg, or placebo for 5 years.
During the study, breast cancer was confirmed in 24 women in the placebo group, 20 in the lasofoxifene 0.25 mg group, and 5 in the lasofoxifene 0.5 mg group.
Compared with placebo, lasofoxifene 0.5 mg significantly reduced the risk for total breast cancer by 79%, and ER-positive invasive breast cancer by 83%.
Adjustment for the Gail score 5-year breast cancer risk estimate did not significantly alter the findings.
In contrast, the risk reduction associated with lasofoxifene was significantly greater among women with baseline estradiol levels above the median (0.35 ng/dl) than those with levels below the median, at 89% versus 22%, respectively.
Lasofoxifene 0.25 mg did not significantly reduce the risk for breast cancer compared with placebo.
The researchers note that lasofoxifene 0.5 mg has also been shown to reduce the risk for vertebral and nonvertebral fracture, coronary artery disease, and stroke in women participating in the PEARL trial.
"The results of this study indicate that a 0.5-mg dose of lasofoxifene has clinical value for breast cancer prevention strategies in postmenopausal women with osteoporosis," LaCroix and co-authors conclude.
They add that its wide spectrum of activity makes it an attractive option for treating these women.
In an accompanying editorial, Victor Vogel from Geisinger Medical Center in Danville, Pennsylvania, USA, said that more information is needed on the long-term beneficial and unfavorable effects of lasofoxifene, "but the early data regarding its risks and benefits are encouraging."
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By Laura Dean