Can breast cancer run in the family, and if so, should I get tested?

Breast cancer can indeed run in families due to an inherited mutation in genes such as BRCA1 or BRCA2. Those mutations considerably increase the risk of breast cancer, although the precise risk differs by gene. BRCA1 and BRCA2 carry the highest risk; there are also other genes that moderately increase the risk. Not everyone with such a mutation will develop breast cancer, but the probability is high enough to take seriously.

Whether you are eligible for a genetic test depends mainly on your family history. Do you have several first- or second-degree relatives with breast cancer, or was someone diagnosed at a young age? If so, it is sensible to discuss this with your general practitioner or a clinical geneticist. A positive test result forms the basis for a more intensive screening programme, so that cancer can be detected earlier.

Carriers who have already had breast cancer at a young age (forty years or younger) may benefit from additional preventive procedures. A large international cohort study involving more than five thousand BRCA carriers showed that the preventive removal of the other breast extended average twenty-year survival by approximately 1.2 years. Removal of the fallopian tubes and ovaries was linked to a comparable gain of around 1.1 years. Both procedures are major interventions and these findings come from observational research, not from a randomised study, so the decision calls for a personal conversation with a specialist.

For people with an established hereditary breast and ovarian cancer syndrome, broad international guidelines exist for risk reduction and adapted screening. Those guidelines are widely supported, although the authors of the ESMO guideline partly have commercial ties with pharmaceutical companies, something to bear in mind when interpreting them.