Family history of breast cancer: what it means for your risk

A family history of breast cancer means that one or more blood relatives have been diagnosed with the disease. Doctors describe relatives by how closely they are related to you. First-degree relatives are your parents, brothers, sisters and children, second-degree relatives include aunts, uncles and grandparents, and third-degree relatives are more distant again.

The NHS lists a family history of breast or ovarian cancer as one factor that may make breast cancer more likely, alongside being over 50, having dense breast tissue and having certain breast conditions. It also explains that some people in these families have inherited a faulty gene, for example a faulty BRCA gene, which raises the chance of developing the disease.

It is important to keep this in proportion. Breast cancer is common, so many families have one or two cases by chance, usually at an older age. NICE guidance for familial breast cancer says that a single relative diagnosed after the age of 40, with none of the warning features below, can in most cases be looked after in primary care and corresponds to a lower 10-year risk than people in higher-risk families.

NICE guideline CG164 sets out when a GP should offer referral to secondary care for a person with no personal history of breast cancer. Written in plain terms, the guideline describes the following situations:

• One first-degree female relative diagnosed with breast cancer before the age of 40.

• One first-degree male relative diagnosed with breast cancer at any age.

• One first-degree relative with cancer in both breasts, where the first cancer was diagnosed before the age of 50.

• Two first-degree relatives, or one first-degree and one second-degree relative, diagnosed with breast cancer at any age.

• One relative with breast cancer and one with ovarian cancer at any age, where at least one of them is a first-degree relative.

• Three first-degree or second-degree relatives diagnosed with breast cancer at any age.

NICE also says a GP should seek advice from the secondary care contact if the family history includes certain additional features alongside breast cancers that do not meet the referral criteria above. These include cancer in both breasts, breast cancer in a man, ovarian cancer, Jewish ancestry, a sarcoma in a relative younger than 45, a glioma or childhood adrenal cortical carcinoma, a complicated pattern of several cancers at a young age, and two or more relatives on the father's side with breast cancer.

The father's side matters. The guideline stresses that a family history should include paternal as well as maternal relatives, because risk-carrying genes can be passed down through either parent. It also recommends asking relatives for details, since the age at diagnosis, the type of tumour and any other cancers all affect the assessment.

If a high-risk gene change such as BRCA1, BRCA2 or TP53 has already been found in the family, NICE says referral should go directly to a specialist genetics service.

The NHS explains that if close relatives have had breast or ovarian cancer you may be eligible for an NHS genetic test, which checks whether you carry a faulty gene that increases cancer risk, such as a faulty BRCA gene. The GP may ask who in the family has had cancer, what type, how old they were at diagnosis and whether the relative is available for testing or has been tested before.

If the GP thinks your risk is increased they will refer you to a specialist breast clinic or genetics clinic for assessment. NICE says specialist services can use carrier probability tools, with CanRisk and the Manchester scoring system given as examples, to estimate how likely it is that a BRCA1 or BRCA2 mutation is present, and that people should be offered a personal risk estimate together with an honest account of its uncertainties.

A result can bring relief or difficult news, and it may have implications for other family members. A genetic counsellor normally talks this through before and after testing.

The NHS says you cannot always prevent breast cancer, but there are steps that lower the chance. It advises cutting down on alcohol and avoiding more than 14 units a week, trying to lose weight if you are overweight and trying to quit smoking. It also suggests speaking to a GP if you are worried about how the contraceptive pill or hormone replacement therapy may affect your risk.

For people at increased risk because of a faulty gene, the NHS says a doctor or genetic counsellor will discuss treatments that can reduce risk, including medicines and, if risk is very high, surgery to remove the breasts (mastectomy), along with the benefits and possible side effects. NICE adds that secondary care should offer mammographic surveillance to the standard of the national breast screening programmes for those who need it.

Whatever your risk, being breast aware matters. The NHS recommends checking your breasts regularly so you know what is normal for you, and going for breast screening when you are invited, because screening can find cancers that are too small to see or feel.

A family history does not change which symptoms matter, but it makes it more important not to wait. The NHS lists a lump or swelling in the breast, chest or armpit, a change in the skin such as dimpling, a change in size or shape, nipple discharge, and a change in the shape or look of the nipple. It says breast pain on its own is not usually a symptom of breast cancer, but you should see a GP if you have breast or armpit pain and other people in your family have had breast or ovarian cancer.

Most breast lumps turn out not to be cancer. The GP will ask about your symptoms and your family history, may examine you, and may refer you to a breast clinic. There you will usually have the tests you need in one visit, which can include an examination, a mammogram, an ultrasound and a needle biopsy, according to the NHS.

Within the NHS, family history is assessed through the GP, a family history or breast clinic and, for the highest-risk families, a specialist genetics service. Eligibility for genetic testing and surveillance follows national criteria, such as those in the NICE guideline, rather than a request alone.

Some people also look at private genetic testing or private breast imaging. These can give results quickly, but they are not a substitute for a proper risk assessment, and a result outside a genetics service may not come with the counselling and follow-up that the NHS pathway provides. It is sensible to discuss any private test with your GP first.