Black women under 65 who are diagnosed with uterine cancer are three times more likely than White women in the same age group to have an aggressive form of the disease, according to a recent Kaiser Permanente study. The research, led by gynecologic oncologist Dr. Betty Suh-Burgmann, is the first to show that the survival gap between Black and White uterine cancer patients widens specifically among younger women, and the first to dig into why that gap exists at all.
The uterine cancer disparity between Black and White women has been documented for years. In the United States, Black women are nearly twice as likely as White women to die from the disease. What researchers hadn’t been able to pin down is why the numbers get worse for younger patients specifically, and whether something fixable, like insurance access, was driving it.
Suh-Burgmann’s team used Kaiser Permanente’s own patient data to answer that question, because it eliminated one major variable other studies couldn’t rule out. Every patient in the system has the same insurance and the same access to care, regardless of race or age. That meant if a survival gap still showed up, insurance coverage couldn’t be the explanation.
It showed up anyway.
The study looked at 13,585 women diagnosed with uterine cancer between 2005 and 2022 across Kaiser Permanente Northern California and Southern California, including 2,055 Black patients and 11,530 White patients. About half the group was under 65 at diagnosis. Researchers found the survival disparity between Black and White patients was 43% wider among the younger group compared to patients 65 and older.
“Understanding why this gap exists is the first step toward addressing it,” Suh-Burgmann said. “We found that the main factor explaining the wider disparity in younger patients is that the increased risk for Black patients to be diagnosed with aggressive type tumors compared to White patients is more pronounced among women under 65.”
The numbers back that up directly. Older Black women were twice as likely as older White women to be diagnosed with an aggressive tumor type. Among younger patients, that risk tripled.
“Whereas older Black women were twice as likely to be diagnosed with aggressive type tumors than older White women, younger Black women were three times more likely to be diagnosed with these tumors compared to their White counterparts,” Suh-Burgmann said.
This builds on an earlier Kaiser Permanente study from the same research team, which found that 71.3% of the overall survival disparity between Black and White uterine cancer patients could be explained by higher rates of aggressive or advanced-stage disease among Black women. Socioeconomic factors accounted for another 18.9% of the gap. It was during that earlier analysis that Suh-Burgmann’s team first noticed the disparity looked wider in women under 65 than in older patients, which pushed them to dig deeper.
Before this study, the leading theory for why younger patients showed a wider gap was insurance. Women under 65 aren’t yet eligible for Medicare, so researchers assumed a lack of coverage might be leaving some patients undiagnosed longer or under-treated. Kaiser Permanente’s setup ruled that out. The researchers also tested other possible factors, including how quickly patients were diagnosed, the treatments they received, other existing health conditions, and general demographics. None of those factors contributed significantly to the age-based gap. Tumor type was the driver.
What’s still unclear is why aggressive uterine tumors show up more often in Black women, and why that risk is even higher in younger patients. Suh-Burgmann said no genetic cause has been identified so far.
“Nobody knows the answer,” she said. “So far, no significant difference has been found in genes known to predispose to cancer. It’s possible that there may be environmental exposures involved, such as pesticides and other toxins. It’s also possible that there may be genes involved that affect susceptibility to environmental exposures and indirectly influence cancer risk.”
There is a piece of encouraging news buried in the data. Suh-Burgmann said survival gaps between Black and White uterine cancer patients appear to be narrowing in recent years, which researchers believe may be tied to advances in chemotherapy, targeted therapy, and immunotherapy for aggressive tumors. As treatment keeps improving, the hope is that the disparity keeps shrinking with it.
Senior author Dr. Julie Schmittdiel said the findings point to a clear next step for researchers.
“Our analysis highlights how important it was to follow up on our initial findings,” Schmittdiel said. “It really shows the need for more research to not only identify why younger Black women are developing these more aggressive tumors but to determine how to provide care that is tailored to this younger population.”
For women wondering what they can do with this information now, recognizing changes in the body matters. According to the CDC, uterine cancer can cause vaginal bleeding or discharge that is unusual for you, including bleeding between periods, heavier than normal bleeding, or any bleeding after menopause. Pelvic pain or pressure can also be a warning sign. The CDC recommends talking to a doctor right away about abnormal bleeding and seeking medical attention for other unusual symptoms that persist for two weeks or longer. The American Cancer Society also notes that there is currently no routine screening test for endometrial cancer in people at average risk who do not have symptoms, making it especially important to report unusual bleeding, spotting, or discharge rather than waiting for a routine screening to catch the disease.
