Breast cancer risk is not increased in estrogen-only HRT but when estrogens are combined with progestins, there is a raised risk that is cumulative. However, there is no evidence of increased mortality and after quitting HRT risk ratios return to normal.
If these data are correct, and if there is a causal or unmasking effect of hormonal therapy on breast cancer, then the rapid reduction in HRT use in America following the Women Health Initiative trial results would have led to a concomitant reduction in cancers detected.
Ravdin et al (NEJM 2007;356:1670-4) report that such a drop in estrogen-receptor-positive breast cancers did occur in 2002-2003 as the number of prescriptions fell from about 50 million to 25 million. This change occurred in postmenopausal women only, strongly implying an association with hormone therapy. The change was of the order of 7% relative risk and the incidence levelled off thereafter.
These findings support a link between combined hormone therapy and breast cancer, but the interpretation should be cautious. The observations concern a particular set of products, a particular age group and a particular type of breast cancer.
The absolute risk of breast cancer for any woman considering hormonal therapy in America remains around 0.30% per annum and this changes to 0.36% per annum on HRT and the effects are cumulative.
This sort of evidence moves our collective wisdom forward but does not answer other questions, such as will these incidences start to rise as the occult cancers reveal themselves later? Or will other forms of hormonal therapy remain free of breast cancer “encouragement”?
So where is the evidence that taking HRT for 10 years after the menopause is harmful?
Is this another example of medicine discovering a magic bullet that is first hailed, then discredited and then, finally, finds its appropriate niche?
JASS certainly believes that the notion of “feminine forever” was a grossly optimistic concept but, equally, there has been an over-reaction to the harmful effects of HRT because of inappropriate hormones given to women long past their menopause - and who were not in the best of health.
Perhaps the pendulum is reaching sanity and hormonal therapy will be useful in the treatment of menopausal symptoms AND offer protection against chronic conditions if used appropriately in terms of initiation, dose, mode of delivery and duration which may well turn out to be 10 years.
The bottom line in 2007 is that starting therapy at the menopause and continuing for a number of years carries little, if any, risk in healthy women. The experts appear in equipoise so it is up to women and their advisors to decide.
It seems clear that initiating combined HRT in women 10 years or more after their menopause does not turn back the clock and probably, on balance, does harm.
