Cervical cancer appears to be rising more rapidly in White women than in Black women in the United States, according to two independent studies. Researchers puzzling over this counterintuitive finding say that, if true, the findings may be a "canary in the coal mine," signaling problems with US healthcare that go way beyond women's health.
Cervical cancer incidence in the United States has plateaued since 2010 and now stands at 7.5 per 100,000 people. Well-known disparities exist: compared with White women, Black women are more likely to have distant-stage disease at diagnosis and more commonly die of their cancer.
However, two unconnected studies published in the past 5 months suggest that White women are catching up fast.
Cervical cancer rates in White women aged 30-34 are rising 2.8% a year, but holding steady for Black women, according to a recent study led by Ashish Deshmukh, PhD, of the Medical University of South Carolina, Charleston. His team analyzed the 2001-2019 National Program of Cancer Registries (NPCR) and Surveillance, Epidemiology, and End Results (SEER) dataset, which covers 98% of the US population and 227,062 cervical cancer cases.
These findings were echoed by an analysis of the same database for 2001-2018 by the University of California Los Angeles (UCLA) suggesting that distant-stage cervical cancer (defined as disease that has spread to the bladder and/or rectum at diagnosis) is climbing 1.69% a year in White people versus 0.67% in Black individuals.
The UCLA researchers, headed by Alex Francoeur, MD, a resident in the Department of Obstetrics and Gynecology, found that disparities were most stark in adenocarcinoma, with an annual increase of 3.40% a year among White women and 1.71% in Black women.
Such findings have equity researchers scratching their heads. In cancer, it's rare to see evidence that Black patients are doing better than their White counterparts.
One theoretical explanation is that the data are flawed, Ahmedin Jemal, DVM, PhD, senior vice-president of Surveillance and Health Equity Science at the American Cancer Society, told Medscape Medical News. For example, the UCLA analysis may have been fogged by changes in staging definitions over time, Jemal commented, although this would not explain the racial disparities per se.
Deshmukh stands by his data and said that, for him, the message is clear: "If rising incidence is not for localized-stage disease, but for advanced stages, that means it's attributable to lack of screening," he told Medscape Medical News.
However, this 'simple' explanation generates even more questions, Deshmukh said: "Screening is not a one-time procedure [but] a spectrum of timely cervical pre-cancer treatment if [required]. We don't know when exactly non-Hispanic White women are falling behind on that spectrum."
The UCLA study supports Deshmukh's conclusions. Using data from the Behavioral Risk Factor Surveillance System to calculate trends in "nonguideline screening," they found that White women were almost twice as likely to report that they were not following screening guidelines compared with Black women over 2001-2016 (26.6% vs 13.8%; P < .001).
"It's not an artifact, it's real," commented Timothy Rebbeck, PhD, the Vincent L. Gregory, Jr. Professor of Cancer Prevention at Harvard, who was not an author of either study and was approached for comment.
"The data are correct but there are so many things going on that might explain these patterns," he told Medscape Medical News.
"This is a great example of complex changes in our social system, political system, healthcare system that are having really clear, measurable effects," Rebbeck said. "Cervical cancer is almost a canary in the coal mine for some of this because it's so preventable."
(The saying "canary in a coal mine" is a warning of danger or trouble ahead. It comes from the time when coal miners would carry a caged canary down into the tunnels to warn them of noxious gases, which would kill the bird but give men time to escape.)
For example, Rebbeck said, recent turmoil in US healthcare has left many people distrustful of the system. Although he acknowledged this was "high speculation," he suggested that some women may have become less willing to participate in any mass healthcare intervention because of their political beliefs.
The UCLA study found that distant cervical cancer was rising fastest in middle-aged White women in the US South, at a rate of 4.5% a year (P < .001).
Rebbeck also suggested that Medicaid expansion — the broadening of health insurance coverage in some states since the Affordable Care Act in 2014 — could be implicated. Of the 11 states that have not yet expanded Medicaid, eight are in the South.
"White populations who are in states that didn't expand Medicaid are not getting a lot of the standard treatment and care that you would expect..." Rebbeck said. "You could very well imagine that Medicaid non-expanding states would have all kinds of patterns that would lead to more aggressive disease."
In fact, there is already evidence that Medicaid expansion has affected racial disparities, disproportionately benefitting Black and Hispanic families, as for example, from this analysis of 65 studies by the Kaiser Family Foundation in 2020.
Commenting on these data, Rebbeck said, "Does that mean that the patterns of advanced cervical cancer had a smaller effect on Black women in this period because there was a greater shift in access to care? This is again a speculation, but it does fit with the 'canary in a coal mine' concept that advanced cervical cancer may be more rapidly influenced by healthcare access than other health conditions."
The authors of the UCLA study suggested another explanation for their results: differing enthusiasm for human papillomavirus (HPV) vaccination among White and Black families. The team also analyzed data on HPV vaccination, which offers protection against cervical cancer. The researchers found that vaccination rates were lowest, at 66.1%, among White teenagers aged 13-17 years, compared with Hispanics at 75.3%, Black teenagers at 74.6%, and Asians at 68.1%.
However, this theory was dismissed by both Jemal and Rebbeck due to timing. HPV vaccines have been around for approximately 15 years, so women who benefitted (or didn't benefit) from vaccination would only be in their late 20s today, they pointed out.
"Ninety-five percent of the cervical cancer cases we see now are in women who have not been vaccinated," said Jemal, "So that's out of the equation."
Rebbeck agreed: "HPV may or may not be a thing here because it's [got] such a latency."
HPV vaccination may be out of the picture, but what about the epidemiology of HPV itself? Could the virus directly or indirectly be boosting advanced cervical cancer in White women?
Deshmukh thinks that it might be doing so.
He published an analysis last month of 2000-2018 SEER data showing that US counties with the highest incidences of HPV-associated cancers also had the highest levels of smoking.
Other recent data suggest that middle-aged White women in the United States are more likely to reach for a smoke than Black women.
Deshmukh acknowledges that the link is speculative but reasonable: "We don't know exactly what the impact of smoking would be in terms of...the ability to clear HPV infection. It may inhibit apoptosis, promoting tumor growth. There's no causal association. It's a cofactor risk."
Rebbeck is also suspicious that smoking patterns might be a factor, pointing out that "smoking is certainly associated with both health behaviors and advanced cervical cancer."
Both Rebbeck and Deshmukh concluded that, at this point, we can only speculate on what's driving the puzzling acceleration of cervical cancer in White women in the United States.
However, whether it's political aversion to screening, smoking-boosted HPV infection, Medicaid expansion or lack of it, or something else, they all agree that this canary in the coal mine clearly needs urgent medical attention.
Rebbeck and Jemal have declared no conflicts of interest. Deshmukh has declared consultant or advisory roles for Merck and Value Analytics Labs. None of the authors of the UCLA study have declared competing interests.
Helen Leask, PhD, CPF, is a freelance science journalist and certified facilitator. She has written for the Canadian Broadcasting Corporation, Maclean's, Quartz, The Globe and Mail, Xtalks, The Walrus, and her own book publishing label, which has published 12 books for patients. She can be reached on Twitter @leask_helen.
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Cite this: Cervical Cancer Rise in White Women: A 'Canary in the Coal Mine' - Medscape - Jan 03, 2023.