Mutations in the BRCA1 and BRCA2 genes are known to increase the risk of female breast and ovarian cancers. But a new study published in the Journal of the National Cancer Institute finds that breastfeeding, taking oral contraceptives and tubal ligation may reduce ovarian cancer risk for women with these mutations.
The BRCA1 and BRCA2 genes are responsible for producing tumor suppressor proteins in the body. These proteins help repair damaged DNA and, in turn, make sure a cell’s genetic material is stable.
A mutation or alteration in either of these genes means proteins are not produced or are impaired; therefore damaged DNA may not be repaired correctly. This can lead to further genetic impairments in cells, which can lead to cancer development.
Women who inherit mutations in the BRCA1 or BRCA2 genes are much more likely to develop breast and ovarian cancers.
According to the National Cancer Institute, mutations in either gene account for approximately 15% of all ovarian cancers. Around 39% of women who inherit a BRCA1 mutation and 11-17% who inherit a BRCA2 mutation will develop ovarian cancer by the age of 70.
The researchers of this latest study, led by Timothy R. Rebbeck, PhD, of the Abramson Cancer Center at the University of Pennsylvania’s Perelman School of Medicine, say past studies have suggested that certain factors – such as smoking and alcohol consumption – may modify the risk of ovarian cancer in women with BRCA mutations.
However, they note that many of these studies “are of variable quality, and it remains unclear which of these may be of value in clinical risk assessment.”
‘Heredity is not destiny’
To gain a better insight into modifiable risk factors for ovarian cancer in BRCA mutation carriers, the research team analyzed 44 peer-reviewed studies that they deemed as having “predefined quality criteria.”
They found that women with BRCA1 mutations who breastfed or who had tubal ligation – a form of birth control in which the fallopian tubes are blocked, tied or cut – had a much lower risk of developing ovarian cancer, compared with women who did not breastfeed or have tubal ligation.
There was no relationship found between breastfeeding and tubal ligation, and reduced risk of breast cancer.
In addition, they found that women with BRCA1 or BRCA2 mutations who used oral contraceptives had a significantly lower risk of ovarian cancer, compared with women who did not use birth control pills.
According to the researchers, the analysis also helped pinpoint factors that may raise cancer risk among women with BRCA mutations. For example, they found that smoking increased the risk of breast cancer for women with a BRCA2 mutation.
Commenting on the team’s findings, Rebbeck says:
“Our analysis reveals that heredity is not destiny, and that working with their physicians and counselors, women with BRCA mutations can take proactive steps that may reduce their risk of being diagnosed with ovarian cancer.
The results of the analysis show that there is already sufficient information indicating how some variables might affect the risk of cancer for these patients.”
Although the researchers found that oral contraceptives may reduce the risk of ovarian cancer, they note that the link between birth control pills and breast cancer was “ambiguous.” Past research has suggested that oral contraceptives increase the risk of breast cancer.
Therefore, the team notes that women should talk to their health care providers and weigh up the potential benefits against potential risks of birth control pills.
The investigators say that more research is needed before any conclusions can be made from their findings, but they point out that their study may help shed light on potential non-surgical options for women at risk of breast and ovarian cancers.
“Patients deserve better cancer-risk reduction options than surgically removing their healthy breasts and ovaries,” says study co-author Dr. Susan Domcheck, of the Basser Research Center for BRCA at the University of Pennsylvania.
“It’s imperative that we continue examining and building upon past research in this area so that we can provide BRCA mutation carriers with options at every age and at every stage of their lives.”