HRT - "Subsequent (2003-2004) Results"

By the end of 2002, we are left with the feeling that there is plenty of data, and that Nelson's meta-study should be successful in summarizing the risks. However, other studies that were published subsequently, demonstrate that some risks from HRT might be even higher than thought.

The "Million Women Study" on the relation between breast cancer and HRT was published in The Lancet (vol 362, p 419, 2003). They find that the relative risk for breast cancer for HRT users is 1.66, (Margin of Error - 1.58 to 1.75 ). This significantly exceeds the 1.23 to 1.35 value found in the meta-study.

Two studies that evolved from WHI, concerning mental decline and HRT were published in JAMA (vol 289, p2651 and 2663, 2003). The studies involved postmenopausal women, 65 years and older. One of the studies measured the participants' global cognitive function using a standard exam. Their conclusion was that HRT did not improve cognitive function compared to a placebo. In fact, there was a small increased risk of cognitive decline in the HRT group. The results also show that HRT increases the risk for "probable dementia" in this population, as a result of HRT - the relative risk is 2.05 (1.21 to 3.48 Margin of Error). These results are at odds with the meta-study result of 0.53-0.82. An editorial by Dr. K. Yaffe in JAMA (v 289, p2717, 2003) notes that such variances between observational studies and randomized trials once again have led to incorrect conclusions (the previous instance concerned CHD in HRT). It emphasizes the need for the more expensive and elaborate randomized trials to determine the effects of various types of treatment.

A recent article in JAMA (v291 p 2947), based on the WHI trials, shows that use of estrogen only also causes an increased risk for dementia. Pooling these results with the previous resuls for estrogen + progesterone, they find a risk ratio of 1.76 (1.19 to 2.60 Margin of Error).

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