Other Risk Factors

How do the risks of taking HRT compare with other risk factors?

To help in understanding how HRT affects your risk you can compare the risks caused by taking HRT with those caused by being overweight.

Being overweight is a risk factor for both breast cancer and heart disease.

Are you overweight?
How to calculate your body mass index (BMI)

Compare your breast cancer risk
Use the table to compare the increased risk of taking HRT compared with the increased risk due to being overweight.

Compare your heart disease risk
Use the table to compare the increased risk of taking HRT compared with the increased risk due to being overweight.

Are you overweight?
In Australia in the year 2000, about 35% of women 45 to 74 years of age were overweight and 30% were very overweight. That is, more than half were either overweight or very overweight.

The definition of being overweight uses an index called the body mass index (BMI), which is calculated from weight and height. According to the World Health Organisation a person is overweight if his or her body mass index (BMI) is 25 to 30, and very overweight if it is 30 or more.

Calculate your BMI

Breast cancer risk: taking HRT compared with being overweight
You can use the table to compare your risk of breast cancer if you take HRT for five years with your risk if you are overweight or very overweight.

It gives the numbers of extra cases of breast cancer in every 1,000 women by age if all 1,000 women took HRT for five years or if they were overweight or very overweight during the five years. These numbers are the extra cases over those that would occur if the 1,000 women were not HRT users or were not overweight.

So, for example, in 1,000 women of 50-54 years of age there would be 6 extra cases of breast cancer if they used HRT for 5 years, 2 extra cases if they were overweight during the 5 years, and 3 extra cases if they were very overweight.

Generally, more women will develop breast cancer if they use HRT than if they are overweight or very overweight for similar periods, but it is not many more.

Heart disease risk: taking HRT compared with being overweight
You can use the table to compare your risk of heart disease if you take HRT for five years with your risk if you are overweight or very overweight.

It gives the numbers of extra cases of heart disease in every 1,000 women by age if all 1,000 women took HRT for five years or if they were overweight or very overweight during the five years. These numbers are the extra cases over those that would occur if the 1,000 women were not HRT users or were not overweight.

So, for example, in 1,000 women of 55-59 years of age there would be 4 extra cases of heart disease if they used HRT for 5 years, 2 extra cases if they were overweight during the 5 years, and 6 extra cases if they were very overweight.

Calculate your BMI

To determine if you are in the healthy weight range, divide your weight (in kilograms) by your height (in metres) squared.

BMI = weight (kg)/height (m)2

For example if you are 155cm (1.55m) tall and weigh 65kg, then you would calculate your BMI as follows:

BMI = 65kg/1.55m x 1.55m = 27kg/m2

According to the WHO, a BMI of 27 would be classified as overweight.

The healthy weight range for a woman 155cm tall would be approximately 45kg to 60kg.