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3-year interval between Pap smears adequate for women with prior negative results

J Fam Pract. 2004 March;53(3):172-188
By
Michael Ohl, MD
Kevin Y. Kane, MD, MSPH
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  • BACKGROUND: The United States Preventive Services Task Force recommends that sexually active women receive Pap smears at least every 3 years. The American Cancer Society also recommends screening every 3 years for women aged >30 years with 3 prior normal Pap smear results.
  • POPULATION STUDIED: The authors analyzed data from the National Breast and Cervical Cancer Early Detection Program (NBCCEDP), which has offered cervical cancer screening to low-income, uninsured women throughout the United States since 1991. Women in this program are disproportionately of lower socioeconomic status and at higher risk for cervical neoplasia.
  • STUDY DESIGN AND VALIDITY: The researchers analyzed the NBCCEDP data to determine the prevalence of biopsy-proven cervical neoplasia in women with 1–3 recent negative Pap smears. They used a Markov model of cervical dysplasia progression to predict the risk of invasive cancer in the next 3 years, assuming yearly follow-up screening or screening 3 years after the last normal result. The definition of prior recent, negative Pap smears included those performed within 3 years of each other and reported as normal or indicating presence of infection or reactive changes.
  • OUTCOMES MEASURED: Measured outcomes were the excess risk of invasive cervical cancer associated with extended screening interval and the number of Pap smears and colposcopies required to prevent 1 case of cancer with more frequent screening.
  • RESULTS: Among women with 3 prior negative Pap smears, the estimated excess risk of cervical cancer associated with screening once at 3 years instead of yearly was 5 per 100,000 for women <30 years of age, 3 per 100,000 for women age 30 to 44, 1 per 100,000 for women 45 to 59, and 0 for women 60 to 64 years of age. Prevention of 1 case of cervical cancer through screening annually rather than once at 3 years would require an additional 42,621 Pap smears and 2364 colposcopies for women aged <30 years; 69,665 Pap smears and 3861 colposcopies for women aged 30 to 44; and 209,324 Pap smears with 11,502 colposcopies for women aged 45 to 59.
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PRACTICE RECOMMENDATIONS

This study predicts that among women aged 30 to 64 years with 3 recent, negative Papanicolaou (Pap) smears, extending the interval for cervical cancer screening from 1 to 3 years would lead to an excess risk of cervical cancer of 3 in 100,000.

For women aged 30 to 44 years, preventing 1 case of cervical cancer through yearly Pap smears would require an additional 69,665 Pap smears and 3861 colposcopies (compared with screening 3 years after the last negative Pap smear). Clinicians should feel comfortable extending the interval for Pap smears from 1 to 3 years in women with prior normal results and a high likelihood of follow-up.

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