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Saway GF, McConnell KJ, Kulasingam SL, et al: Risk of cervical cancer associated with extending the interval between cervical cancer screenings. N Engl J Med 2003;349(16):1501-9.
Feldman S: How often should we screen for cervical cancer? N Engl J Med 2003;349(16):1495-6 (editorial).
Despite guidelines indicating that the interval between screenings for cervical cancer can be lengthened for many women, both providers and patients have been reluctant to change it. These authors used data from a relatively high-risk cohort of women who were enrolled in the National Breast and Cervical Cancer Early Detection Program. They estimated the rate at which dysplasia will progress to cancer within 3 years after one or more negative Papanicolaou tests using a Markov model. Among 31,728 women aged 30 to 64 years who had three or more consecutive negative tests, the prevalence of biopsy-proven cervical intraepithelial neoplasia of grade 2 was 0.028% and the prevalence of grade 3 neoplasia was 0.019%; none of the women had invasive cervical cancer.
If 100,000 women were screened annually, rather than every 3 years, one additional case of cervical cancer would be averted, but in women aged 45 to 59, 209,324 additional Papanicolaou tests and 11,502 colposcopic examinations would be needed. These additional tests are both costly and emotionally upsetting to the patient, without materially affecting the rate of cervical cancer. For patients who are in low-risk categories and are known to comply with screening advice, it is reasonable to lengthen the screening interval to 3 years after three negative Papanicolaou tests. For women in higher-risk categories such as those with a history of cervical dysplasia or immunosuppression, or who do not comply with screening recommendations, annual screening is advised.