Hormone replacement therapy: risks & benefits

This topic is a controversial one because of a study by the Women's Health Initiative (WHI) which suggested that using hormone replacement therapy (HRT) increased a woman's risk of developing breast cancer and cardiovascular disease. While there are important risks and benefits that need to be discussed before one begins on HRTs, it is important to be critical when considering the implications of the WHI study.



A few things to note

1. The average age of women enrolled in WHI was 65, which is about a decade older than the average age of menopausal women, which is when we normally prescribe HRT. Older women are more likely to encounter disease as compared to their younger counterparts.
2. The adverse effects of HRT are also dose related. This means the longer you use it (>5 years) the more significant the adverse effects. So the aim would be to use the lowest dose possible to achieve therapeutic effect and to consider weaning off at about 3-5 years.
   
3. The WHI study did not find a statistically significant increase in the risk of developing breast cancer. The increase risk was approaching statistical significance and even then, was for women who had used HRT for more than 5 years.

Menopausal symptoms
HRTs are the most effective means of reducing menopausal symptoms, in particular the vasomotor symptoms such as hot flushes and sweating.

Alternatives: SSRIs, SNRIs, black cohosh

Breast Cancer
Current or past hormone-dependent cancer is an absolute contraindication.
Strong family history is a relative contraindication (ie. proceed with caution)
Minimally increased in women taking HRT >5years (+8 of 10000 women)
Risk trends back to normal when you stop taking HRTs.
Breast cancer mortality does not change even if you take HRTs because the type of cancer is less aggressive and there is close follow-up care.

Other Cancers
Endometrial cancer - if estrogen used alone then there is an increased risk. We counter this effect on the endometrial lining by using estrogen & progestin together.With combined therapy there is actually decreased risk.
Colorectal cancer - decreased in women taking HRTs. (-8 of 10 000 women)
Given the minimally increased risk of breast cancer and the minimally decreased risk of colorectal cancer, there is no overall change in incidence of cancer when a woman takes HRTs.

Cardiovascular risk
In younger women (HRT started within 4 years of menopause) exogenous estrogen is protective against cardiovascular disease. However, it does not reverse cardiovascular disease that is already present before you start HRTs.

If you start HRT 20 years after menopause, combined HRT (estrogen and progestins) may increase cardiovascular risk.

Cardiovascular risk related to HRT decreases over time.

Thromboembolic disease and Stroke risk
HRTs doubles the risk of thromboembolic disease (ie. DVTs) and as such patients will also be at increased risk for stroke (+7 of 10 000 women).

Sources: eTG (this requires a subscription), 

**See the disclaimer**