Menopause news

Could HRT really reduce risk of breast cancer?

29 Sept 2008

After some years of hearing about risks of HRT, we now are being told that in fact it reduces the risk of breast cancer in high-risk women. There is no doubt that this latest news, from a Canadian study, will further add to the already confusing web through which women and their doctors and nurses have to weave!

The facts are that for many years we have been aware of an association of a small increased risk of breast cancer when HRT is used for more than 5 years after the age of 50. Over recent years it has become clear that this small risk applies to combined HRT, (estrogen combined with progestogen), rather than estrogen only HRT, (the type used after a hysterectomy), and indeed the Women’s Health Initiative trial suggested a reduced risk of breast cancer in women using estrogen only. Against the issue of breast cancer must be balanced the benefits of effective control of menopausal symptoms with improved quality of life, protective effect on bone leading to reduced risk of osteoporosis and osteporotic fractures, and, when used within 10 years of the menopause or under the age of 60 years, a likely, though not absolutely confirmed, beneficial effect on the heart and risk of heart disease. Despite these benefits, many women have been reluctant to use HRT, and many doctors reluctant to prescribe it, because of the main concern of breast cancer. This has been particularly of concern to women who, for example because of genetics, are already at high risk of developing breast cancer, approximately 3% of invasive breast cancers being attributed to a genetic mutation in BRCA1 or BRCA2.
So what does the information from this new study add? The Canadian study followed through 472 postmenopausal women (either naturally or surgically menopausal), who were at high risk of breast cancer because of the BRCA1 gene, to examine whether or not the use of HRT was associated with subsequent risk of breast cancer. Women who carry a BRCA1 gene mutation have a lifetime risk of breast cancer of 60-80%. The risk can be reduced by removing the ovaries before the menopause, the reduced risk thought to be due to withdrawal of ovarian hormones, but then concern is raised if hormone therapy is needed after the operation, or after natural menopause, in that theoretically the benefit of the reduced risk could be negated.

The study in fact showed that the women who took HRT had a 42% reduction in risk of developing breast cancer. This was greatest in women taking estrogen only (49%), which was statistically significant, compared to those taking estrogen combined with progestogen (34%).

Limitations of the study are that it was a relatively small study, and was observational, rather than randomized. However, a previous study by Rebbeck has also shown that there was no reduction in the benefit of removal of ovaries in terms of breast cancer risk in women with BRCA1 mutation carriers, if HRT was taken after surgery.

In summary, although it would be premature to, at this stage, look on HRT as a protector against breast cancer, we can be reassured that the risk of breast cancer associated with HRT use seems to be very small, especially with estrogen only, and even in women who are at high risk of breast cancer. For most women, when it is used appropriately, the benefits of HRT continue to far outweigh the risks.

[Ref.]

Full article: oxfordjournals.org

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