My Breakthrough
Risk of hereditary breast cancer
The estimated risks of developing hereditary breast cancer are based on the number and age of family relatives that have been affected by breast cancer.
Levels of risk
A risk estimate is expressed as the increased chance of developing breast cancer compared to the risk in the general population.Whilst having a higher personal risk of cancer than the general population means that you are more likely to develop breast cancer, it does not mean that you will definitely get the disease in
the future.
Whilst having a higher personal risk of cancer than the general population means that you are more likely to develop breast cancer, it does not mean that you will definitely get the disease in the future.
The levels of risk are broadly defined as:
Population risk
Most breast cancer has no known hereditary basis and occurs in women with no significant
family history.
About 80% of breast cancer cases occur in women more than 50 years old (after the menopause). This means that every woman has some risk of developing breast cancer and that risk increases as she gets older.
- The risk for any woman of developing breast cancer at some point in their lifetime is 11%. That is to say 1 in 9 women will develop breast cancer at some point in their lifetime.
- Women with no significant family history have a risk of developing breast cancer that is said to be near to population risk (this is sometime referred to as average risk and means that there is no increase in risk above that of the general population).
- The National Institute for Health and Clinical Excellence (NICE) familial breast cancer guideline states that a family history that gives an estimated risk of less than 17% or a 1 in 6 lifetime chance of developing breast cancer does not indicate a significant family history and is therefore considered to be near to population risk.
- The vast majority of women are at or near population risk.
Moderate risk
- Women with a moderate family history of breast cancer are at moderate increased risk of developing breast cancer. Being at moderate risk does not mean that you will definitely develop breast cancer. However, it does mean that you have a greater chance of developing breast cancer than someone who is at population risk.
- Moderate risk is defined in the NICE familial breast cancer guidelines as between a 17 and 30% or between a 1 in 6 and 1 in 3 chance of developing breast cancer at some point in your lifetime.
- It has been estimated that about 13% or approximately 1 in 8 women more than 20 years old are at moderate risk of developing breast cancer because of their family history.
High risk
Only about 5% or 1 in 20 cases of breast cancer are due to hereditary factors, the majority of which are known
about at present.
- Women with a strong family history have a high risk of developing breast cancer. Being at high risk does not mean that you will definitely develop breast cancer. However, being at high risk means that you have a greater chance of developing breast cancer than someone who is at moderate or population risk.
- High risk is defined in the NICE familial breast cancer guidelines as a greater than 30% or 1 in 3 chance of developing breast cancer at some point in your lifetime.
- Less than 1% of all women are at high risk.
