Study shows breast cancer risk for women with BRCA1 gene abnormalities on ‘the pill’

Certain women are at a greater risk of breast cancer the longer they use hormonal contraceptives like the pill, a new study has found.

Women with BRCA1 gene abnormalities have an increased risk of breast cancer the longer they use hormonal contraceptives, such as “the pill”.

That’s the finding of a new study led by the Peter MacCallum Cancer Centre and Cancer Council Victoria.

The details were presented on Friday at a major breast cancer symposium in Texas in the US with the lead researchers saying the results should inform, but not alarm, women at risk.

Roger Milne, head of Cancer Epidemiology at Cancer Council Victoria, is co-lead and said the observational research analysed information collected from four major studies in Australia, Europe, Canada and the US over three decades.

Peter MacCallum Cancer Centre medical oncologist, Professor Kelly-Anne Phillips presented the results in Texas on Friday. Picture: supplied

He said they involved almost 5400 women who had inherited BRCA1 and BRCA2 abnormalities, but who did not have cancer when they joined the studies.

Most of the women had BRCA1 abnormalities and, among these, the researchers said 488 later developed breast cancer.

BRCA1 and BRCA2 are genes which usually help protect against breast cancer, and women who inherit an abnormal version of one of these genes are at a high risk of breast cancer.

Professor Milne said abnormalities in these genes are rare, occurring in 1 in 400 (or 0.2%) of the Australian population.

Those with these inherited abnormalities account for about five per cent of all cases of breast cancer.

The observational study looked at four major long-term studies. Image: Supplied.

“Women with BRCA1 abnormalities who used hormonal contraceptives, such as the pill, for at least a year, had increased risk of subsequently developing breast cancer compared with women who did not use hormonal contraceptives,” co-lead of the research Kelly-Anne Phillips said.

A medical oncologist at Peter Mac, Professor Phillips said the team found breast cancer was more common in the women who used a hormonal contraceptive for longer.

She says more research is needed to properly understand if these contraceptives also affect breast cancer risk in women with BRCA2 abnormalities as the results of this study for BRCA2 were inconclusive.

Professor Milne said women with BRCA1 abnormalities should talk to their general practitioners for advice.

“We know that there is an increased risk, and that risk increases the longer you use hormonal contraception,” he said.

“But these medications also provide excellent contraception and can have other health benefits, such as reducing the risk of endometrial and ovarian cancers. This needs to be weighed carefully against the possible increase in breast cancer risk.

“This is all about giving women information to make an informed decision.”

Professor Phillips presented the findings on Friday at the San Antonio Breast Cancer Symposium.

Originally published as Study shows breast cancer risk for women with BRCA1 gene abnormalities on ‘the pill’