Mortality rates from cervical cancer in the Unites States have been seriously underestimated in the past because they were not corrected by including among the data a history of hysterectomy, say researchers.
A new study that uses estimates corrected for a history of hysterectomy, published online January 23 in Cancer, has found that the risk of black women dying from cervical cancer is 77% higher than previously reported. For white women, the risk for death from the same disease is 47% higher.
"This is a preventable disease, and women should not be getting it, let alone dying from it," study leader Anne Rositch, PhD, MSPH, assistant professor of epidemiology, Johns Hopkins Bloomberg School of Health, Baltimore, Maryland, said in a statement.
"These findings motivate us to better understand why, despite the wide availability of screening and treatment, older and black women are still dying from cervical cancer at such high rates in the United States."
The researchers point out that a hysterectomy completely removes the risk of women developing cervical cancer, unless a cervix-sparing surgical procedure is performed.
In the past, women with a hysterectomy were not excluded from previous calculations of mortality from cervical cancer, the researchers note in a press statement. Given that 1 in 5 women in the United States undergo a hysterectomy — with rates slightly higher among black women — including a history of hysterectomy in these calculations clearly makes a sizeable difference, they add.
For their study, the investigators used national survey data to estimate the age, race, year, and state-stratified prevalence of hysterectomy. "We then used those estimates to correct the denominator of equivalently stratified cervical cancer mortality rate estimates," lead author Anna Beavis, MD, MPH, Johns Hopkins Bloomberg School of Health, explained. The Surveillance, Epidemiology and End Results mortality database was used to obtain mortality rates from cervical cancer, she added.
"Overall, the prevalence of hysterectomy was 20%...for women ≥20 years old...and was higher for black women than white women [at] 23% vs 21%, (P < .05)," the investigators report.
The prevalence of hysterectomy peaked between the ages of 65 and 69 years for both white and black women, but more black women underwent hysterectomy at these ages than did white women (58% vs 43%, P < .05), they add.
For both races and for white and black women separately, the corrected age-standardized mortality rate from cervical cancer was appreciably higher both overall and for each race separately than the uncorrected mortality rate.
Table. Age-Standardized Hysterectomy-Corrected vs Uncorrected Mortality Rates From Cervical Cancer: 2000 to 2012
|Uncorrected Mortality Rates||Corrected Mortality Rates|
|White and black women combined||3.4/100,000||5.0/100,000|
In 2012, GLOBOCAN estimated that the cervical cancer mortality rate for women living in developed nations was only 3.3 per 100,000.
In contrast, the same organization found that the corrected estimate for black women living in the United States was as high as rates seen in women living in sub-Saharan Africa and was on par with those reported in developing regions, such as the Caribbean and Latin America.
In their article, Dr Beavis and colleagues state that whether mortality rates were corrected for hysterectomy or not, "age-specific cervical cancer mortality rates were significantly higher for black women than white women in all age categories except [for women aged] 20 to 29 and 35 to 39 years."
The greatest increase in age-specific corrected cervical cancer mortality rates was observed in black women between 65 and 69 years of age, among whom rates increased by more than 126% compared to uncorrected cervical cancer rates during the study period.
The equivalent increase for white women in the same age category was nearly half that, at 75%, the investigators add.
More disturbingly, the risk for death from cervical cancer among black women aged 85 years and older (who are long past the age for which PAP screening is recommended) is highest of all, at a corrected rate of 37.2 per 100,000, vs an uncorrected rate of 18.6 per 100,000 — a 101% increase in corrected cervical cancer mortality rates compared to uncorrected rates.
Currently, screening guidelines call for routine PAP smears for women between the ages of 21 and 65, after which PAP screening is no longer recommended if three consecutive prior tests have been negative.
"These data tell us that as long as a woman retains her cervix, it is important that she continue to obtain recommended screening for cervical cancer, since the risk of death from the disease remains significant well into older age," Dr Rositch said in a statement.
In an accompanying editorial, Heather Dalton, MD, and John Farley, MD, both from the Creighton University School of Medicine in Phoenix, Arizona, discuss potential reasons why black women might have worse overall survival rates than white women with the same disease, an observation that unfortunately holds true across almost all cancer types in the United States, they note.
"Differences in histology may contribute to disparities across ages and races," Dr Dalton and Dr Farley observe. Specifically, adenocarcinoma is associated with a worse prognosis for both early- and late-stage cervical cancer compared with squamous cell carcinoma. Currently, "rates of adenocarcinoma in black women increase with age, whereas they plateau at the age of 35 years in white women," the editorialists note.
Moreover, as is true for many other cancer types, black women often present with later-stage disease compared to white women, and there are also differences in the care they receive. In particular, black women are much less likely to undergo surgery and to receive radiation therapy than white women.
"Data suggest that women at high risk for cervical cancer either do not have adequate access to preventive services or choose not to use preventative services," Dr Dalton and Dr Farley add, although they note that this does not hold true universally.
The current analysis offers a few "glimmers of hope," they point out. First, corrected cervical cancer mortality rates are narrowing between black and white women, and differences in mortality between the two races were virtually eliminated in younger patients aged 20 to 29 and 35 to 39 years.
"This is notable because these age cohorts correspond to the patients who are most likely to have been vaccinated against the human papillomavirus (HPV) virus," Dr Dalton and Dr Farley note.
"And although it will take decades to observe decreases in HPV-related cervical cancer, the prevalence of the HPV strains included in the quadrivalent vaccine has already [declined by] 64% among vaccinated teen girls," they add.
The study was partially funded by a research grant from the Cigarette Restitution Fund to the Johns Hopkins Medical Institutions. One of the study authors has received reagent and travel support from Hologic for research not related to the study. Dr Farley has received personal fees from Genentech.