Blood test for ovarian cancer misses some Black and Native American
patients, study finds
[March 21, 2025]
By CARLA K. JOHNSON
A common blood test may miss ovarian cancer in some Black and Native
American patients, delaying their treatment, a new study finds. It's the
latest example of medical tests that contribute to health care
disparities.
Researchers have been working to uncover these kinds of biases in
medicine. Recently, the Trump administration’s crackdown on diversity,
equity and inclusion has jeopardized such research as universities react
to political pressure and federal agencies comb through grants looking
for projects that violate the president's orders.
Native American women have the highest rate of ovarian cancer. Black
women with ovarian cancer have lower rates of survival compared to white
women. Finding ovarian cancer early can lead to better chances of
survival.
The new study, supported by grants from the National Cancer Institute
and published Thursday in JAMA Network Open, looked at a test called
CA-125. The test measures a tumor marker in the blood, and doctors use
it to determine if a woman with a suspicious lump should be referred to
a cancer specialist.
Doctors depend on the test during early evaluations, so understanding
what the results mean for people of different races and ethnicities is
critical, said Dr. Shannon Westin of MD Anderson Cancer Center in
Houston, who was not involved in the research.
“This is a perfect example of work that absolutely needed to be
stratified based on race and ethnicity," Westin said. The findings alert
doctors that they shouldn't be totally reassured by a normal test
result, she said.
So far, it’s unknown why the test doesn't perform uniformly across
groups. The researchers suspect it has something to do with a harmless
genetic variation that is more common in people of African, Caribbean,
Middle Eastern and West Indian descent.
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The National Institutes of Health's James Shannon building is seen
on the agency's campus in Bethesda, Md., Friday, Oct. 24, 2014. (AP
Photo/Pablo Martinez Monsivais, File)
 Initial studies of the test,
published in the 1980s, didn’t record people’s races but were in
mostly white populations.
The test isn't perfect for white women either, said lead author Dr.
Anna Jo Smith of the University of Pennsylvania's medical school.
“But if we have worse performance in certain groups, then we may be
further contributing to disparities in referral, disparities in
treatment, and ultimately we may be contributing to the lower
survival in Black women with ovarian cancer," Smith said.
The researchers analyzed data from more than 200,000 women with
ovarian cancer from 2004 through 2020 who'd had a CA-125 blood test.
Black and Native American patients were 23% less likely to have an
elevated CA-125 level at ovarian cancer diagnosis compared with
white patients, suggesting the current thresholds are set too high.
The researchers also found that patients with false negative results
started chemotherapy on average nine days later than patients with
elevated levels. That could make a difference for some patients,
Smith said.
Last week, Smith and her colleagues presented work at a Society of
Gynecologic Oncology meeting proposing a new lower threshold for the
blood test that would work better across all populations. The work
could lead to changes in guidelines.
“New thresholds for referral will ensure that all patients get in
for rapid care when ovarian cancer is suspected,” Smith said.
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