Though BRCA1 or BRCA2 gene mutations are associated with breast and ovarian cancer in younger women, those over 50 continue to have a high risk of breast cancer.
That's true even if they didn't have breast cancer earlier, new research shows.
“What is striking about our results is that breast and ovarian cancers were the most frequently observed cancers occurring and that is concerning, considering we know how to reduce the risk of cancer in women who have these genetic risk factors,” said study leader Kelly Metcalfe, a professor on the University of Toronto faculty of nursing.
To study this, her team followed more than 2,200 women between 50 and 75 years of age from 16 countries. These women were aware they had a BRCA mutation and had no previous diagnosis of cancer.
The risk that these women would develop any type of cancer after age 50 was 49% for those with a BRCA1 mutation and 43% for those with a BRCA2 mutation.
It was even higher for those who hadn't had a cancer risk-reduction surgery, such as preemptive removal of both breasts, both ovaries and fallopian tubes. For those women, the risk was 77% for those with a BRCA1 mutation and 67% for those with a BRCA2 mutation.
About 15% of women studied had undergone a preventive bilateral mastectomy. About 43% had both ovaries and fallopian tubes removed before age 50.
These women had the lowest risk of any cancer at just 9%.
“Our analysis highlights the effectiveness of these risk reduction surgeries and emphasizes the need for individuals as well as health care providers, to consider clinical guidelines and recommendations for their cancer risk, including how their genetics might impact them even at a later age,” Metcalfe said in a university news release.
She noted that access to risk reduction surgeries may be limited in some countries -- a limitation of the study. Researchers did not assess whether or how often or women received genetic counseling.
“We are not aware of whether the participants in our study received additional counseling about their elevated risk of cancer as they age and we are also unable to determine why some of these women chose to forgo preventative surgery before the age of 50,” Metcalfe said. “However, it is important to point out that screening alone only reduces [death] risk by increasing the chances of detecting the cancer early, it does not reduce the risk of cancer occurring.”
No good screening method exists for ovarian cancer. National Comprehensive Cancer Network guidelines recommend that women with a BRCA1 mutation have ovaries and fallopian tubes removed between ages 35 and 40 and those with BRCA2 mutation between ages 40 and 45.
Metcalfe hopes that advances in genetic testing will help more women know their risks. Future studies will look at women's decision-making about surgery and their understanding of risk.
Low barriers to genetic testing will save lives, said Metcalfe, who expects it to become a mainstay of cancer care in Canada. Regardless of family history, people can pay a small fee to be tested BRCA1 and BRCA2 mutations through Screen Project Canada.
“It has been over 25 years since clinical testing for BRCA1 and BRCA2 began in Canada and the United States, we have come a long way in reducing cancer incidence, but not far enough,” Metcalfe said. “The majority of cancers resulting from these two genes are preventable, we need to be offering women the best chance at a cancer-free life.”
Study findings were recently published in the journal Cancer.
The U.S. Centers for Disease Control and Prevention has more on the BRCA1 and BRCA2 genes.
SOURCE: University of Toronto, news release, Feb. 24, 2023