By: Stephen Matthews
BRCA mutations, made famous by the Hollywood actress who was a carrier, are known to heighten the chance of developing the deadly disease.
But before now, scientists were unable to provide an accurate percentage for how much the genetic twists raise the risk individually.
The latest Cambridge University-led study of more than 10,000 women gives the most precise estimates to date, researchers claim.
The findings will enable doctors to provide better advice and counselling for women who carry the genetic twists.
Three quarters of women carriers of a faulty BRCA1 gene will go on to develop breast cancer by age 80, the researchers found.
This figure is compared to 69 per cent of those with a BRCA2 mutation, the experts noted in JAMA.
For ovarian cancer, the risk was 44 per cent for those with the former mutation and much lower at 17 per cent for the latter.
However, for both cancers, a woman’s family history affected the risk and made the carrier slightly more likely.
‘Now we understand’
Study co-author Professor Gareth Evans, of Manchester University, said the results of the research helped paint a clear picture.
He said: ‘Now that we understand more clearly the risks faced by women who carry these genetic faults, we would be in a better position to counsel them about the outcomes from screening and prevention programmes.
‘This will also have practical implications on clinical management decisions, for example on the timing of surgery in order to reduce cancer risk.
‘Such decisions tend to be taken around childbearing age, but some women with lower risks may opt to delay surgery until they complete their families.’
Lead author Dr Antonis Antoniou said: ‘We have been able to provide the most precise estimates of age-specific risks to date.
These should provide more confidence in the counselling and clinical management of women with faults in the BRCA1 and BRCA2 genes.’
Why is the risk needed?
Advances in technology have opened up the potential of screening all women for BRCA1 and BRCA2 mutations.
However, such population-based screening depends on reliable risk estimates to provide to women with and without a family history of the disease.
Percentage risks are also needed for women who are known to carry the fault, as it enables them to determine what action to take.
After Jolie had a double mastectomy in 2013 when she found out her increased risk of breast cancer because of the genetic fault, millions of women have followed suit.
Breast reconstruction usually involves using tissue from another part of the patient’s body – a practice that is painful and leaves multiple scars.
Many also rush to get tested, and – in many cases – proceed to get their breasts removed, sometimes unnecessarily.
Women also sometimes decide to have their ovaries removed if they are at an increased cancer risk, leaving them infertile – despite not knowing the true risk.
The previous risk calculation
Previous studies addressing the risk were based on study designs that assessed women who already had cancer.
The only way to provide a more accurate result is through prospective cohort studies which follow carriers over time.
However, before this one, the largest was based on just 64 patients.
Barbara Jacoby is an award winning blogger that has contributed her writings to multiple online publications that have touched readers worldwide.