Lead author Anne F. Rositch, an assistant professor at the University of Maryland School of Medicine and the University of Maryland Marlene and Stewart Greenebaum Cancer Center, said U.S. cervical cancer screening guidelines do not recommend routine Pap smears for women age 65 and older if their prior test results were normal.
Today's age-standardized rate of about 12 cases of cervical cancer per 100,000 U.S. women reaches a peak at age 40 to 44 and then levels off.
However, Rositch and colleagues found these estimates included women who had hysterectomies in which the lower part of the uterus, the cervix, was removed.
The study, published online in the journal Cancer, found that if the women who had hysterectomies were excluded from the calculation because they are no longer at risk of developing cervical cancer the rate increased to 18.6 cases per 100,000 women. The cervical cancer incidence increased with age but peaked in women ages 65 to 69.
For women ages 65 to 69 the cervical cancer rate was 27.4 cases per 100,000 women -- 84 percent higher than the uncorrected rate of 14.8 cases per 100,000 women.
For white women ages 65 to 69, the rate was 24.7 cases per 100,000, higher than the uncorrected rate of 13.5 cases per 100,000. The rate for African-American women ages 65 to 69 was 53 cases per 100,000, higher than the uncorrected rate of 23.5 cases per 100,000.
"Our corrected calculations show that women just past 65, when current guidelines state that screenings can stop for many women, have the highest rate of cervical cancer," Rositch said in a statement.
"It will be important to clarify in future studies whether the continued increase in cervical cancer rates with age and the higher rates in African-American women represent a failure in our screening programs or a failure of the women to be screened so that appropriate interventions can be applied."
Human papillomavirus infections cause virtually all cervical cancers, and the findings highlight the need for widespread HPV vaccination to protect women against cervical cancer, the researchers said.