Post-menopausal women who use female hormone supplements containing estrogen and progestin ("combination" therapy) are at an increased risk for estrogen receptor positive breast cancer, says a new study.
The study found that the overall increase in risk was 50 percent, with greater increases for recent and long-term users.
Prior epidemiologic studies have been based largely in white women, which stated, use of combination therapy was associated with an increased risk of estrogen receptor positive breast cancer, the most commonly occurring breast cancer subtype, which is known to be sensitive to hormonal factors.
Whether postmenopausal female hormone therapy has the same effects in black women has been unknown up to this point.
Researchers from the Boston University in the US led an investigation of this association in data from the four large studies of black women.
Two types of postmenopausal female hormone use, combination therapy and use of estrogen alone were assessed in relation to risk of estrogen receptor positive and negative breast cancer.
Similar to findings in white women, use of combination therapy was associated with increased risk of estrogen receptor positive breast cancer, with risk increasing as the duration increased.
"The present findings establish that combination therapy in black women is associated with increased risk of estrogen receptor positive breast cancer, similar to the pattern in white women," explained co-author Lynn Rosenberg from the Slone Epidemiology Centre in the US.
The risk declined after cessation of use but was still somewhat elevated up to 10 years later.
There was no increase in risk associated with use of estrogen alone, nor was there any increase in risk of estrogen receptor negative breast cancer associated with use of either combination therapy or estrogen alone.
The study appeared in the Journal of the National Cancer Institute.
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