Risks of HRT

Foot Notes

1. IMS Updated Recommendations on postmenopausal hormone therapy. Climacteric 2007:10;181-194.
2. British Menopause Society Council Consensus Statement. Alternative and Complementary Therapies. 5 June 2007. http://www.thebms.org.uk/statementcontent.php?id=2
3. Medicines and Healthcare products Regulatory Agency (MHRA) Drug Safety Update. Vol 1 Issue 2 September 2007.
4. Rossouw JE et al. Postmenopausal hormone therapy and risk of cardiovascular disease by age and years since menopause. JAMA 2007;297:1465-77.

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Breast cancer risk in perspective

Combined HRT use and breast cancer risk

Breast cancer risk in comparison
Risk factor	Relative risk	Increase in risk
HRT in Women’s Health Initiative study (WHI: combined Estrogen + Progestogen product)1	1.24	+ 24%
Early Menarche (first menstruation before age of 11)2	1.3	+ 30%
Late first pregnancy (after age of 35)3	1.4	+ 40%
Nulliparity (women who have never given birth)3	1.3	+ 30%
Daily moderate alcohol consumption (>20g/day; equal to 0.5 l beer or 0,25 l wine)4	1.3	+ 30%
Obesity (being overweight) with Body Mass Index > 34kg/m2 (BMI=Weight(Kg)/Height2(m2))5	2.5	+ 150%

1. Chlebowski RT, Hendrix SL, Langer RD et al, JAMA 2003;289:3243-53.
2. Kvale G. Acta Oncol. 1992;31:187-94.
3. Ewetz M, Duffy SW, Adami HO et al, Int. J. Cancer 1990;446:597-603 Chen WY, Colditz GA, Rosner BR et al, Ann. Int. Med. 2002;137:798-804.
4. Morimoto LM, White E, Chen Z et al, Cancer Causes Control 2002;13:741-751 Then Women’s Health Initiative Steering Committee, JAMA 2004;291:1701-1712.
5. Burger H et al, Climacteric, 2004;7:210-216.

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Breast cancer

Current advice from the International Menopause Society is that HRT taken for less than 5 years does not significantly increase the risk of a diagnosis of breast cancer, but some studies suggest a small increased risk after 5 years of use. The relationship between HRT and a diagnosis of breast cancer is complex and it is still not entirely clear whether HRT causes breast cancer or speeds up its development. It has recently been estimated that 5 cases of breast cancer would normally be expected to be diagnosed in 1000 women aged 50-59 followed for five years and not taking HRT. If the same 1000 women took HRT for five years, there an additional six diagnoses of breast cancer might be expected³.

Women who have, have had or suspect to have breast cancer as well as those with a strong family history should avoid taking HRT.

Practical recommendations: breast cancer in perspective

Venous thrombosis (blood clot in a vein)

• It has been known for a long time that taking the contraceptive pill increases risk of venous thrombosis. This can lead to a deep vein thrombosis (DVT) and the clot may travel to the lung to cause a pulmonary embolism. It is known that HRT also increases this risk. Overall the risk of any healthy woman having a venous thrombosis is very small.
• It is estimated that around 5 out of every 1000 healthy women aged 50 - 59 years and not taking HRT might experience a venous thrombosis over a 5 year period. There will be approximately 7 additional cases of venous thrombosis in 1000 women taking HRT, over and above the 5 events which would occur anyway. In women aged 60-69, there would be around 10 extra venous thromboses per 1000 women using HRT for five years, over and above the 8 cases that might occur in non-users of HRT³.
• Venous thrombotic events are more likely to occur in the first year of using HRT. See your doctor if you develop a red, swollen or painful leg or have sharp chest pains.

Heart disease and stroke

Older research studies suggested that HRT might help prevent heart disease and strokes. Recent large studies have not confirmed this and in fact some have shown that HRT may slightly increase the risk of stroke and heart disease.

However, women who started HRT closer to menopause tended to have a reduced risk of heart disease compared with the increased risk among women initiating HRT late after menopause⁴.

The IMS states that in women less than 60 years old, who are recently menopausal and who do not have existing heart disease, starting HRT does not appear to cause early harm to the heart and blood vessels, however the prevention of heart disease is not a reason for giving HRT.

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