According to a new study published in Cancer, the peer-reviewed journal of the American Cancer Society (ACS), rates of cervical cancer in the U.S. may be higher than previously thought, and cervical cancer may occur most often after age 65, when women are advised to stop getting screened. What's more, cervical cancer rates may be higher in black women.

The U.S. Centers for Disease Control and Prevention recommends regular cervical cancer screenings, which are done with Pap tests or HPV tests, for all women between the ages of 21 and 65.

The ACS’s guidelines state that women between the ages of 21 and 29 should have a Pap test every three years, and that they should not be tested for HPV unless it is needed after an abnormal Pap test result. In addition, the ACS recommends that women between the ages of 30 and 65 should have both a Pap test and an HPV test every five years. This is the preferred approach, but it is also okay to have a Pap test alone every three years.

The ACS advises women over age 65 who have had regular screenings with normal results to not be screened for cervical cancer. Women who have been diagnosed with cervical pre-cancer should continue to be screened.

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Prior Rates Based on Women Who Had Hysterectomies

Previous estimates of cervical cancer rates in the U.S. have included women who have had the uterine cervix removed through a hysterectomy. This surgery eliminates a woman’s risk of developing cervical cancer.

Lead study author Anne Rositch, assistant professor of epidemiology and public health at the University of Maryland School of Medicine in Baltimore, told Healthline,  "We found that because older women and African American women had the highest prevalence of hysterectomy, the corrected rate estimates resulted in the largest increase for these groups of women compared to the uncorrected rates. Incidence rates of cervical cancer increased with age up to age 65 to 69 years, unlike the uncorrected rates, which tapered off after age 45 year."

Rositch and her colleagues analyzed hysterectomy prevalence and cervical cancer incidence from 2000 to 2009. Overall, incidence rates were 11.7 cases per 100,000 women before correcting for hysterectomies, compared with 18.6 per 100,000 after correction. In addition, previous reports showed that the incidence peaks at age 40 to 44 years (15.6 cases per 100,000 women) and then levels off.

After correcting for hysterectomy, the incidence continued to increase with age, climbing to 27.4 cases per 100,000 women at age 65 to 69 years. The effect was most noticeable among black women, who have a higher prevalence of hysterectomy than white women.

Before correcting for hysterectomies, figures indicated that black women had a 62 percent higher rate of cervical cancer than white women. After ignoring hysterectomies, the researchers learned that black women had an 89 percent higher rate than white women.

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Women Over 65 Have Highest Rate of Cervical Cancer

Senior study author Patti Gravitt, Ph.D., of the Johns Hopkins Bloomberg School of Public Health, said in a press statement, “Current guidelines recommend exiting women with recent negative screening from routine screening at age 65 years, and yet our corrected calculations show that women just past this age have the highest rate of cervical cancer.”

Finally, commenting on the future implications of the study, Rositch told Healthline, "The disparity between white and African American women was greater than previously recognized using our corrected calculation for cancer incidence rates. Thus, to understand both the clinical and policy implications, it will be important to conduct additional research to understand whether the high rates in these two groups of women are due to screening failures (screening failed to detect the cervical precancers and cancers) or failure to be screened (women had not obtained the recommended screening). Our study sheds new light on the women in the U.S. who are at the highest risk of cervical cancer, older women, 65 to 69 years, not middle aged women, and African American women."