Only about 25% of women diagnosed with breast cancer and about 31% of women diagnosed with ovarian cancer have genetic testing to see if the cancer may be linked to an inherited genetic mutation, according to a study.
The research was published online on April 9, 2019, by the Journal of Clinical Oncology. Read the abstract of “Genetic Testing and Results in a Population-Based Cohort of Breast Cancer Patients and Ovarian Cancer Patients.”
This research comes after a study published in December 2018 showing that current National Comprehensive Cancer Center Network (NCCN) breast cancer genetic testing guidelines miss about half of people with a genetic mutation linked to breast cancer.
What is hereditary breast cancer?
About 5% to 10% of breast cancers are thought to be hereditary, caused by genetic mutations passed from parent to child. Three of the most well-known genes that can mutate and raise the risk of breast and/or ovarian cancer are BRCA1, BRCA2, and PALB2. Women who inherit a mutation, or abnormal change, in any of these genes — from their mothers or their fathers — have a much higher-than-average risk of developing breast cancer and/or ovarian cancer. Men with these mutations have an increased risk of breast cancer, especially if the BRCA2 gene is affected, and possibly of prostate cancer. Many inherited cases of breast cancer have been associated with mutations in these three genes.
You are substantially more likely to have a genetic mutation linked to breast cancer if:
- you have blood relatives (grandmothers, mother, sisters, aunts) on either your mother's or father's side of the family who had breast cancer diagnosed before age 50
- there is both breast and ovarian cancer on the same side of the family or in a single individual
- you have a relative(s) with triple-negative breast cancer
- there are other cancers in your family in addition to breast, such as prostate, melanoma, pancreatic, stomach, uterine, thyroid, colon, and/or sarcoma
- women in your family have had cancer in both breasts
- you are of Ashkenazi Jewish (Eastern European) heritage
- you are African American and have been diagnosed with breast cancer at age 35 or younger
- a man in your family has had breast cancer
- there is a known genetic mutation linked to breast cancer in your family
Current genetic testing guidelines
Current NCCN guidelines recommend genetic testing for someone diagnosed with breast cancer if:
- there is a known mutation in the family
- the person was diagnosed at age 50 or younger
- the person has been diagnosed with two primary breast cancers
- a first-degree female relative (mother, sister) was diagnosed with breast cancer at age 50 or younger or was diagnosed with ovarian cancer
- two or more first-degree relatives were diagnosed with breast, prostate, and/or pancreatic cancer
- a man in your family has been diagnosed with breast cancer
The NCCN is an alliance of a group of the world's leading cancer centers. These NCCN centers collaborate on research, guidelines, and education to improve the care of people diagnosed with cancer.
How this study was done
To do this study, the researchers looked to see how many women living in California and Georgia who had been diagnosed with breast or ovarian cancer between 2013 and 2014 had genetic testing.
The study included 77,085 women diagnosed with breast cancer and 6,001 women diagnosed with ovarian cancer.
“We initiated this study … because we wanted to see what cancer genetic testing and results looked like in the real world,” Allison Kurian, M.D., of Stanford University, who was the lead author of the study, said in an interview.
- 24.1% of women diagnosed with breast cancer had genetic testing
- 30.9% of women diagnosed with ovarian cancer had genetic testing
Women who were older when diagnosed with breast cancer and women who lived in areas with high poverty rates were less likely to have genetic testing. For women diagnosed with breast cancer, race and ethnicity didn’t seem to affect genetic testing rates.
Among women diagnosed with ovarian cancer, women who were age 40 to 59 had the highest levels of genetic testing. Women who lived in areas with high poverty rates were less likely to have genetic testing. Women diagnosed with ovarian cancer who were Black, single, and had Medicaid insurance were less likely to have genetic testing.
Genetic test results
Among women diagnosed with breast cancer, 3 times more women were tested for mutations in BRCA1 and BRCA2 genes than any other mutations. The most common mutations linked to breast cancer found were:
- BRCA1: 3.2%
- BRCA2: 3.1%
- CHEK2: 1.6%
- PALB2: 0.96%
- ATM: 0.73%
Mutations also were found in the BARD1, CDH1, NBN, NFI, and TP53 genes.
Only 1.9% of the women diagnosed with breast cancer were tested for mutations in all 11 genes identified in current guidelines as breast cancer susceptibility genes.
Among women tested for mutations in these 11 breast cancer susceptibility genes, 7.8% had an actionable mutation linked to breast cancer. An actionable mutation means having the mutation can lead to changes in treatment, screening, and risk-reduction strategies.
Among women diagnosed with ovarian cancer, nearly twice as many women were tested for mutations in BRCA1 and BRCA2 genes as were tested for any other NCCN-designated mutation linked to ovarian cancer. The most common mutations linked to ovarian cancer found were:
- BRCA1: 8.7%
- BRCA2: 5.8%
- BRIP1: 0.92%
- MSH2: 0.79%
- RAD51C: 0.58%
Women diagnosed with ovarian cancer had similar rates of mutations in the CHEK2 (1.4%) and ATM (0.64%) genes as women diagnosed with breast cancer. Still, CHEK2 and ATM mutations are not linked to a higher risk of ovarian cancer.
About 14% of women diagnosed with ovarian cancer were tested for mutations in all 11 genes identified in current guidelines as ovarian cancer susceptibility genes.
Among women tested for mutations in these 11 ovarian cancer susceptibility genes, 14.5% had an actionable mutation linked to ovarian cancer.
What this means for you
This study adds to other research strongly suggesting that many people with mutations linked to breast cancer are not having genetic testing.
“Genetic testing has become quite cheap and accessible, and this study includes a time period when it was becoming much cheaper, so it’s striking that we still see low rates of testing,” Kurian said. “I think that suggests that there are most likely other barriers outside of cost. These findings have uncovered a [disparities] gap that is much more substantial than I would have thought.
“Testing is recommended for all patients with ovarian cancer,” she continued, so the fact that only one-third of these patients had it done in this time period “is a clear-cut example that we’re not testing ovarian cancer patients the way that we should be.”
There are a number of reasons why someone diagnosed with breast or ovarian cancer might want to consider genetic testing:
- Women who have a BRCA1 or BRCA2 mutation can benefit from a class of medicines called PARP inhibitors. Three PARP inhibitors are approved to treat BRCA1- and BRCA2-associated ovarian cancer and two PARP inhibitors are approved to treat BRCA1- and BRCA2-associated metastatic breast cancer.
- Anyone with a genetic mutation linked to breast or ovarian cancer has a higher risk of a second cancer, so more frequent screening is usually recommended.
- If a person has a genetic mutation, every first-degree relative — sisters, brothers, sons, and daughters — has a 50% risk of having the same mutation. Having this knowledge can allow for enhanced screening and prevention steps for loved ones who also may have the mutation.
If you’ve been diagnosed with breast cancer or ovarian cancer, you may want to talk to your doctor or a licensed certified genetic counselor about your diagnosis and your family history and ask if having a multigene panel test makes sense for you. A licensed certified genetic counselor or your doctor can help you understand the test and accurately interpret the results.
For more information on genetic testing, including types of genetic tests and how results are reported, visit the Breastcancer.org Genetic Testing pages.
For more information on genes and genetic mutations linked to breast cancer, as well as all the risk-lowering steps you can take if you have a genetic mutation, visit the Breast Cancer Risk Factors: Genetics page in the Breastcancer.org Lower Your Risk section.
To discuss being at high risk for breast cancer with other people, join the Breastcancer.org Discussion Board forum High Risk for Breast Cancer. If you've tested positive for a mutation linked to breast cancer and would like to talk about this with others who have also tested positive, join the forum Positive Genetic Test Results.
Written by: Jamie DePolo, senior editor
Reviewed by: Brian Wojciechowski, M.D., medical adviser