Fewer Women with Ovarian, Breast Cancer Undergo Genetic Testing than Expected

Health news

Fewer
Women with Ovarian, Breast Cancer Undergo Genetic Testing than Expected

Tests
for inherited genetic mutations
can provide women diagnosed with ovarian or breast cancer
with important information that can have implications for family members and
potentially guide treatment decisions and longer-term screening for second
cancers. However, many women with ovarian and breast cancers are
not receiving these genetic tests, a new study suggests.

An NCI (affiliated
to U.S. Department of Health and Human Services)-funded analysis of data on
more than 83,000 women from large cancer registries in California and Georgia
found that, in 2013 and 2014, only about one-quarter of women with breast
cancer and one-third of women with ovarian cancer underwent testing for known
harmful variants in breast and ovarian cancer susceptibility genes.

The study
also found that among patients who did receive genetic testing, 8% of breast
cancer patients and 15% of ovarian cancer patients had “actionable” gene
variants, meaning variants that might warrant changes in treatment, screening,
and risk-reduction strategies.

The
findings, published April 9, 2019, in the Journal of Clinical Oncology, were
surprising, especially the low rate of testing among women with ovarian
cancerExit Disclaimer, said lead author Allison Kurian, M.D., M.Sc., of
Stanford University School of Medicine.

“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,” Dr. Kurian said. “I think that suggests that there are
most likely other barriers outside of cost.”

The study
also revealed racial and socioeconomic disparities in testing rates among women
diagnosed with ovarian cancer. Genetic testing rates were far lower for black
women than for white women, and they were also lower for uninsured patients
than for insured patients.

“These
findings have uncovered a [disparities] gap that is much more substantial than
I would have thought,” Dr. Kurian said.

Reasons
and Recommendations for Genetic Testing

About 15% of
ovarian cancers are caused by inherited mutations, and several medical
organizations recommend that all women diagnosed with ovarian cancer receive
genetic testing.

Genetic
counseling and testing for women with breast cancer

For women
with breast cancer, the recommendations for genetic counseling and testing are
generally more limited, typically relying on factors such as age at cancer
diagnosis and family history. However, some organizations, including the
American Society of Breast Surgeons, recommend that genetic testing be made
available to all women diagnosed with breast cancer.

There are
many reasons why women with ovarian and breast cancer would get tested, Dr.
Kurian explained.

“We know
that if patients have a specific inherited gene mutation, they will likely have
more benefit from a new class of drugs called PARP inhibitors,” she said.

The Food and
Drug Administration has approved three PARP inhibitors for BRCA1- and BRCA2-associated
ovarian cancer and two for BRCA1- and BRCA2-associated metastatic breast
cancer. Harmful variants of both BRCA1 and BRCA2 are known to increase the risk
of breast and ovarian cancer, as well as of several other types of cancer.

“Another
reason to get tested is that patients with a genetic mutation that is
associated with breast or ovarian cancer may be at higher risk of a second
cancer, so you don’t want to miss a second cancer that could be a problem,” Dr.
Kurian said.

“The
findings could also be life-saving information for a patient’s relatives. If
you find that she carries a mutation, every first-degree relative, male or
female, has a 50% chance of having the same mutation,” she said.

Testing,
then, could allow for enhanced screening and prevention for family members who
are carriers, she explained.

A
“Baseline” Population-Based Genetic Testing Study

The study
included all women older than age 20 who were diagnosed with breast or ovarian
cancer in California and Georgia from 2013–2014 and whose data were reported to
NCI’s Surveillance, Epidemiology and End Results (SEER) registries. There were
77,085 patients with breast cancer and 6,001 with ovarian cancer. The registry
data were linked to results from four laboratories that performed nearly all
the genetic testing for inherited, or germline, mutations in these states
during the study period.

According to
the authors, this is the first population study of hereditary cancer genetic
testing in the United States with laboratory-confirmed testing results.

“We’ve never
had this kind of linkage available before, giving us a baseline to let us know
if the standard of care [for testing] was being followed,” said study coauthor
Lynne Penberthy, M.D., M.P.H., associate director for NCI’s Surveillance
Research Program. “That’s why this is really important. These data can be used
to see where we are and where we’re going. We can continue to provide this
information, so people can see, hopefully, an increase in the appropriate use
of genetic testing over time.”

Linking the
SEER registry data to the testing data in this study provides “really objective
data about the massive undertesting of ovarian cancer patients,” said Susan
Domchek, M.D., executive director of the Basser Center for BRCA at the
University of Pennsylvania Abramson Cancer Center, who was not involved in the
study.

“Testing is
recommended for all patients with ovarian cancer,” she added, 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.”

Unexpected
Disparities and Low Testing Rates

While large
racial and socioeconomic disparities in testing rates were not observed among
women with breast cancer, among women with ovarian cancer, testing rates were
far lower in black women than white women (21.6% versus 33.8%) and in uninsured
women than insured women (20.8% versus 35.3%).

Understanding
why genetic testing rates are so low in women with ovarian cancer and why
racial and socioeconomic disparities in testing exist among women with the
disease is tricky, Dr. Kurian said.

“Testing in
ovarian cancer has not been widely studied before—definitely not at the
population level—and not in such a diverse population,” she added, “so there’s
a lot we don’t know about barriers.”

For example,
she said, it’s unclear whether genetic testing is on the radar screen of
doctors treating patients with ovarian cancer as much as it is for patients
with breast cancer. Dr. Domchek said there could also be misconceptions among
patients about the costs of genetic testing.

“But if
access to genetic counseling or information on testing is difficult, clearing
up these misconceptions can be a challenge,” she said. “So, trying to figure
out how to better streamline [counseling and education] into practice to make
sure all of these individuals with ovarian cancer get tested is a subject of
ongoing research.”

Dr. Domchek
noted that NCI is looking to fund studies that offer genetic testing to women
with a personal or family history of ovarian cancer to see if it can help to
identify members of their families who may be at increased cancer risk.

More Than
BRCA

Although
variants in the BRCA1 and BRCA2 genes were the most frequently found in the
study, the laboratories also looked for other inherited cancer-related genetic
mutations using tests known as multigene panels.

The results
provide “an understanding, on a broader scale, of how common these mutations
are,” Dr. Kurian said.

The
multigene panel testing led to other noteworthy findings, Dr. Penberthy said.

“What was
really interesting was that while BRCA1 and BRCA2 were the most common germline
mutations that we found in the study, there were other mutations that were not
uncommon and that were actionable in terms of treatment as well,” she
explained.

For example,
60 women with breast cancer in the study had a mutation in the CDH1, PALB2, or
PTEN genes. These mutations are associated with a substantially increased
breast cancer risk, Dr. Kurian said, so women who have these mutations may
consider having both breasts removed (a risk-reducing bilateral mastectomy),
rather than just the breast in which the tumor was found.

And widely
used clinical guidelines recommend that women with breast cancer who have
certain inherited genetic mutations, including in genes such as ATM and CHEK2,
undergo more intensive screening for second cancers. In the study, mutations in
ATM and CHEK2 were found in 0.7% and 1.6% of women with breast cancer,
respectively.

Mutations in
CHEK2 and PALB2 and several other genes were found both in women with breast
cancer and women with ovarian cancer. Studies haven’t yet linked these genes
with increased ovarian cancer risk, so further study is warranted, the authors
wrote.

However, the
key message from this study is the undertesting of ovarian cancer patients, who
clearly need it, Dr. Domchek said.

“It’s not to say we shouldn’t debate population screening [for inherited mutations], or which genes to test for, and how we’re going to do it,” she said. “But first, for heaven’s sake, let’s test the people who absolutely need testing, not only because it impacts family members, but also because now we have first-line therapy with PARP inhibitors. Every woman with ovarian cancer should know her BRCA1 or BRCA2 status.”

“Fewer Women
with Ovarian, Breast Cancer Undergo Genetic Testing than Expected was
originally published
by the National Cancer Institute.”

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