Genetic testing after a breast cancer diagnosis is becoming more common. Researchers wondered how genetic test results were being used to make decisions about treatment if a woman had been diagnosed with early-stage disease.
A study suggests that genetic test results are not being clearly communicated to women and may be causing them to opt for treatment that is more aggressive than they need.
The research was published online on May 12, 2017 by the Journal of Clinical Oncology. Read the abstract of “Gaps in Incorporating Germline Genetic Testing Into Treatment Decision-Making for Early-Stage Breast Cancer.
Up to 10% of breast cancers are thought to be hereditary, caused by gene mutations -- a harmful change in the gene -- passed from parent to child.
Genes are particles in cells, contained in chromosomes, and made of DNA (deoxyribonucleic acid). DNA contains the instructions for building proteins. And proteins control the structure and function of all the cells that make up your body.
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 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.
The function of the BRCA and PALB2 genes is to keep breast cells growing normally and prevent any cancer cell growth. But when these genes contain the mutations that are passed from generation to generation, they do not function normally and breast cancer risk increases.
Because people are more aware of the genetic mutations linked to breast cancer, the demand for genetic counseling and testing has increased. It’s been difficult for genetic counselors to keep up with this demand, especially in areas with few counselors.
To do this study, the researchers sent a survey on genetic testing to 2,502 women who had been diagnosed with stage 0 to stage II breast cancer between 2014 and 2015. The women were between 20 and 79 years old and lived in Georgia and Los Angeles, Calif. The surveys were mailed about 2 months after the women were diagnosed. After excluding women who didn’t have genetic testing and women who had been diagnosed with cancer in both breasts, the researchers analyzed the responses from 666 women.
Because 98% of the women reported the name of their surgeon in the survey, the researchers also sent genetic testing surveys to the surgeons.
The characteristics of the women were:
- 56% white, 18% black, 14% Hispanic, and 9% Asian
- 64% were 50 or older when they completed the survey
- 16% had another serious health condition, such as diabetes, chronic obstructive pulmonary disease, or stroke
- before genetic testing, 39% of the women were considered to be at average risk of having a genetic mutation and 59% were considered to be at high risk
The characteristics of the cancers were:
- 22% were stage 0, 48% were stage I, and 27% were stage II
- 22% were grade I, 40% were grade 2, and 34% were grade 3
- 9% were estrogen-receptor-positive
- 72% were estrogen-receptor-positive and progesterone-receptor-positive
- 66% were HER2-negative
- 10% were HER2-positive
- 82% had no lymph nodes involved
The researchers found that a surgeon was the health professional who most often ordered the genetic testing, especially for women considered to be at high risk of a mutation:
- 48% of high-risk women and 42% of average-risk women had genetic testing ordered by their surgeon
- 31% of high-risk women and 40% of average-risk women had genetic testing ordered by their medical oncologist
- 21% of high-risk women and 18% of average-risk women had genetic testing ordered by a genetic counselor
While most of the women discussed genetic test results with a genetic counselor, there were still a large percentage of women who never talked to a counselor:
- 57% of high-risk women and 42% of average-risk women talked to a genetic counselor
- 19% of high-risk women and 18% of average-risk women talked only to their surgeon
- 17% of high-risk women and 31% of average-risk women talked only to their medical oncologist
- 7% of high-risk women and 10% of average-risk women talked to multiple healthcare professionals
Most of the women had genetic testing before surgery, which means the test results could be used when making treatment decisions. Still, about one-third of the women had genetic testing after surgery, which means that the results were not used to inform surgery decisions:
- 6% of high-risk women and 2% of average-risk women had testing before being diagnosed
- 67% of high-risk women and 64% of average-risk women had testing after being diagnosed but before breast cancer surgery
- 27% of high-risk women and 34% of average-risk women had testing after breast cancer surgery
The genetic test results showed:
- 72% of the women had no genetic mutation linked to higher breast cancer risk
- 9% had genetic variants of uncertain significance; these are genetic changes that are not linked to a higher risk of cancer
- 7% had a BRCA1, BRCA2, or other mutation linked to higher breast cancer risk
About 12% of the women didn’t report their genetic testing results.
A total of 377 surgeons completed the survey:
- 38% saw 1-20 breast cancer patients in the past year
- 30% saw 21-50 breast cancer patients in the past year
- 29% saw 51 or more breast cancer patients in the past year
Surgeons who treated more patients with breast cancer were more confident about discussing genetic test results with patients.
About 33% of the surgeons rarely referred patients for genetic counseling and ordered genetic testing without a referral.
Half of the surgeons who saw only a few breast cancer patients and 25% of surgeons who saw many breast cancer patients reported treating women with a variant of uncertain significance the same as women who tested positive for a BRCA1 or a BRCA2 mutation.
The researchers then compared the genetic testing results to the treatment the women had. They found that about half of the women who had double mastectomy, meaning both the breast with cancer and the other healthy breast were removed, did not have a genetic mutation linked to a higher risk of breast cancer. Instead, they had variants of uncertain significance.
"That was a bit surprising, because we wouldn't typically expect that surgery to be conducted for women if they don't have a risk-causing gene mutation," said Allison Kurian, M.D., associate professor of medicine, health research and policy at Stanford University and lead author of the study.
"Our findings suggest a limited understanding among physicians and patients of the meaning of genetic testing results," she continued. "Clinical practice guidelines state that variants of uncertain significance should not be considered to confer high cancer risk, and that patients with these variants should be counseled similarly to a patient whose genetic test is normal. However, many of the physicians surveyed in our study stated that they manage these patients in the same way as they do patients with mutations known to increase a woman's risk."
"Some women may be making these decisions because they are not fully understanding that their risk is not terribly different from average-risk women," said Robert Smith, vice president of cancer screening for the American Cancer Society. "Rather aggressive therapy decisions are perhaps being made in the absence of careful, competent discussion about what this means."
"The gaps identified in this study are striking," said Reshma Jagsi, M.D., professor and deputy chair of radiation oncology at the University of Michigan and another study author. "It is critical to ensure that patients at high risk for known cancer-associated mutations are fully informed of the potential benefits of genetic testing and counseled accurately about the meaning of test results."
"We're learning that clinicians' knowledge of breast cancer genetics can be highly variable," said Dr. Kurian. "It's important for women at high risk of carrying a dangerous mutation to see someone with expertise in cancer genetics when planning their care. Unfortunately, in many cases genetic counselors may not be optimally integrated into the care of newly diagnosed cancer patients, making it difficult to rapidly triage these patients. Our study highlights the urgent need for improved patient access to cancer genetics experts, particularly genetic counselors, and for educating physicians about the appropriate use of genetic testing and interpretation of test results."
If you and/or some of your family members have been diagnosed with breast cancer, you may be interested in the possibility of genetic testing.
A mutation linked to a higher risk of breast cancer is more likely to run in your family if:
- Many women in your family have had breast and/or ovarian cancer, particularly at a younger age than these cancers typically develop (before age 50).
- Some women in your family have had cancer involving both breasts.
- There is both breast and ovarian cancer in your family.
- Men in your family have had breast cancer.
- There is breast cancer in your family and either male relatives on the same side of the family have had prostate cancer at a young age, or male or female relatives on the same side of the family have had gastrointestinal cancers, such as cancer of the pancreas, gall bladder, or stomach.
- Your family is of Ashkenazi (Eastern European) Jewish descent.
If any of these are true for either side of your family, you may be a candidate for genetic testing. If you’ve been diagnosed with breast cancer, you may want to meet with a genetic counselor before breast cancer surgery. As the results of this study show, talking to an expert about how to interpret your genetic testing results can be very important when you’re making surgery decisions. To find a genetic counselor who specializes in family-related cancer risk, talk to your doctor or check with the hospitals and cancer centers in your area. If your surgeon doesn’t refer you to a genetic counselor, you may have to advocate on your own behalf.
For more information on genetic testing and counseling, visit the Breastcancer.org Genetic Testing pages.