Who Should Not Take Hormone Replacement Therapy (HRT)?

Who shouldn't take hormone therapy (HT)?

HT is not usually recommended for women who have:

• Active or past breast cancer
• Recurrent or active endometrial cancer
• Abnormal vaginal bleeding that has not been evaluated
• Recurrent or active blood clots
• History of stroke
• Known or suspected pregnancy

Breast cancer

Women who have been taking HRT for more than 1 year have a higher risk of breast cancer than women who have never used HRT. Risk is associated with all types of HRT, except vaginal estrogen. For women in their 40s and 50s who take HRT for 5 years, it would be as follows:

• 1 extra case for every 200 women taking oestrogen-only HRT
• 1 extra case for every 70 women taking cyclical HRT
• 1 extra case for every 50 women taking continuous HRT

The number of additional cases is thought to double among women who have been taking these types of HRT for 10 years. Research shows that the increased risk of breast cancer falls after you stop taking HRT, but there is still some increased risk for more than 10 years compared to women who have never used HRT.

If you take it less than 1 year, there is little or no increased risk of breast cancer. Because of the risk of breast cancer, it is particularly important to take part in all your breast cancer screening appointments if you are taking HRT.

Womb cancer

Oestrogen-only HRT can increase the risk of cancer of the womb (also called uterine or endometrial cancer), which is why it is only used in women who do not have a womb (for example, because they have had hysterectomy). Taking combined HRT, in particular a continuous combination of HRT (where you take both medicines without a regular break), largely eliminates this risk. If you have a womb and you are taking HRT, it is important to take both medicines, as advised by your doctor, to avoid increasing your risk of cancer of the womb.

Blood Clots

Blood clots can be serious if they get trapped in a blood vessel and block the flow of blood. Evidence indicates that:

• Taking HRT tablets may increase your risk of blood clots
• There is no increased risk of blood clots from HRT patches or gels

The risk of developing a blood clot is thought to be 2 to 4 times higher than normal for women taking HRT tablets. However, since the risk of menopausal women developing blood clots is usually very low, the overall risk of taking HRT tablets is still small. It is estimated that for every 1,000 women taking HRT tablets for 7.5 years, less than 2 will develop a blood clot.

Heart disease and strokes

The evidence shows that:

• HRT does not significantly increase the risk of cardiovascular disease (including heart disease and stroke) at an early age of 60 years.
• Oestrogen-only HRT is associated with no or decreased risk of heart disease.
• The combination of HRT is associated with little or no increase in the risk of heart disease.
• Taking oestrogen tablets is associated with a small increase in the risk of stroke, but the risk of stroke for women under the age of 60 is generally very low, so the overall risk is still small.