A blood test used to check for ovarian cancer may not work as well for Black and Native American women, a new study suggests.

This could lead to delays in treatment and poorer health outcomes.

The study, published in JAMA Network Open, looked at more than 200,000 women with ovarian cancer who took a test called CA-125. This test checks for a tumor marker in the blood that can be a sign of cancer. Doctors often use it to decide if a woman should be sent to a cancer specialist.

Researchers found that Black and Native American patients were 23% less likely to have high levels of CA-125 when diagnosed with ovarian cancer compared to white patients. 

That means the test may miss cancer in these groups more often.

“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,” lead author Dr. Anna Jo Smith, an assistant professor of gynecologic oncology at the University of Pennsylvania, told The Associated Press.

The test wasn’t originally designed with all groups in mind. Early research from the 1980s shows initial studies were mostly in white populations, which may explain why the test works better for some people than others.

One possible reason for the difference is a harmless genetic trait that’s more common in people with African, Caribbean, Middle Eastern or West Indian ancestry.

The study also found that women who got a false negative result started chemotherapy nine days later than those with high levels.

Smith and her team recently shared new research at a cancer conference suggesting a lower threshold for the test. This new limit is intended to better detect ovarian cancer across all populations.

“New thresholds for referral will ensure that all patients get in for rapid care when ovarian cancer is suspected,” Smith said.

Dr. Shannon Westin of MD Anderson Cancer Center in Texas, who was not part of the study, said this study illustrates why it’s important to study how medical tests work in different racial and ethnic groups.

“This is a perfect example of work that absolutely needed to be stratified based on race and ethnicity,” Westin said, adding that the findings alert doctors that they shouldn’t be totally reassured by a normal test result.

More information

The City of Hope has more on ovarian cancer diagnosis and treatment.

SOURCE: The Associated Press, March 20, 2025

Source: HealthDay

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