Is Hormone Therapy Safe for Breast Cancer Survivors?
They noted that the risk of breast cancer developing in the previously unaffected breast was higher among HRT users than nonusers.
"The idea that this therapy would actually be beneficial to breast cancer patients, in the sense that it lowers recurrence, is completely contrary to our understanding of breast cancer and how it grows," Jack Cuzick, PhD, of the Imperial Cancer Research Fund in London, tells WebMD. "Everything we know suggests this treatment couldn't really be beneficial. But in fact, the ... evidence [from this study] does suggest this is a real possibility. And we have been fooled before."
Cuzick, who wrote an editorial accompanying O'Meara's study, says even if HRT turns out to have no effect on the prognosis of breast cancer, it could be a great benefit for survivors with menopausal symptoms. The findings from this study give "added support and urgency" to trials of HRT in menopausal women with breast cancer that are now under way in Sweden and the U.K., he adds.
American Cancer Society spokeswoman Debbie Saslow, PhD, agrees that larger studies with different designs are needed to confirm that HRT is safe for women with a history of breast cancer. Women and their doctors cannot assume the therapy is safe based on just this study, she says, because patient numbers were small, follow-up times were short, and most patients had very early stage breast cancers at diagnosis.
"If this study does anything, I would say that it may help calm concerns about very short-term therapy in women treated for these early stage cancers," she says. "If a woman who fits this profile needs a very short-term therapy fix with HRT to get her past the most severe period of menopause symptoms, that may be safe."
Saslow points out that 80% of the women included in the study were treated with estrogen alone, instead of estrogen plus progestin. The combination treatment is more widely associated with breast cancer risk, she adds.
"The type of hormone therapy these women were taking has a much smaller effect on their breast cancer risk," she says. "This is a very important point that was not really brought out by the authors."