Current approaches and challenges to cervical cancer prevention in the United States
A digest of cervical cancer screening options and new tools and innovations that may help reduce cervical cancer rates—along with equitable preventive care and increased HPV vaccination rates
Primary HPV screening
Primary HPV testing means that an HPV test is performed first, and if it is positive for high-risk HPV, further testing is performed to determine next steps. This contrasts with the currently used method of obtaining cytology (Pap) first with either concurrent HPV testing or reflex HPV testing. The first HPV primary screening test was approved by the US Food and Drug Administration (FDA) in 2014.13
Multiple randomized controlled trials in Europe have demonstrated the accuracy of HPV-based screening compared with cytology in the detection of cervical cancer and its precursors.14-17 The HPV FOCAL trial demonstrated increased efficacy of primary HPV screening in the detection of CIN 2+ lesions.18 This trial recruited a total of 19,000 women, ages 25 to 65, in Canada and randomly assigned them to receive primary HPV testing or liquid-based cytology. If primary HPV testing was negative, participants would return in 48 months for cytology and HPV cotesting. If primary liquid-based cytology testing was negative, participants would return at 24 months for cytology testing alone and at 48 months for cytology and HPV cotesting. Both groups had similar incidences of CIN 2+ over the study period. HPV testing was shown to detect CIN 2+ at higher rates at the time of initial screen (risk ratio [RR], 1.61; 95% confidence interval [CI], 1.24–2.09) and then significantly lower rates at the time of exit screening at 48 months (RR, 0.36; 95% CI, 0.24–0.54).18 These results demonstrated that primary HPV testing detects CIN 2+ earlier than cytology alone. In follow-up analyses, primary HPV screening missed fewer CIN 2+ diagnoses than cytology screening.19
While not as many studies have compared primary HPV testing to cytology with an HPV cotest, the current most common practice in the United States, one study performed in the United States found that a negative cytology result did not further decrease the risk of CIN 3 for HPV-negative patients (risk of CIN 3+ at 5 years: 0.16% vs 0.17%; P=0.8) and concluded that a negative HPV test was enough reassurance for a low risk of CIN 3+.20
Another study, the ATHENA trial, evaluated more than 42,000 women who were 25 years and older over a 3-year period.21 Patients underwent either primary HPV testing or combination cytology and reflex HPV (if ages 25–29) or HPV cotesting (if age 30 or older). Primary HPV testing was found to have a sensitivity and specificity of 76.1% and 93.5%, respectively, compared with 61.7% and 94.6% for cytology with HPV cotesting, but it also increased the total number of colposcopies performed.21
Subsequent management of a primary HPV-positive result can be triaged using genotyping, cytology, or a combination of both. FDA-approved HPV screening tests provide genotyping and current management guidelines use genotyping to triage positive HPV results into HPV 16, 18, or 1 of 12 other high-risk HPV genotypes.
In the ATHENA trial, the 3-year incidence of CIN 3+ for HPV 16/18-positive results was 21.16% (95% CI, 18.39%–24.01%) compared with 5.4% (95% CI, 4.5%–6.4%) among patients with an HPV test positive for 1 of the other HPV genotypes.21 While a patient with an HPV result positive for HPV 16/18 should directly undergo colposcopy, clinical guidance for an HPV-positive result for one of the other genotypes suggests using reflex cytology to triage patients. The ASCCP recommended management of primary HPV testing is included in the FIGURE.22
Many barriers remain to transitioning to primary HPV testing, including laboratory test availability as well as patient and provider acceptance. At present, 2 FDA-approved primary HPV screening tests are available: the Cobas HPV test (Roche Molecular Systems, Inc) and the BD Onclarity HPV assay (Becton, Dickinson and Company). Changes to screening recommendations need to be accompanied by patient and provider outreach and education.
In a survey of more than 500 US women in 2015 after guidelines allowed for increased screening intervals after negative results, a majority of women (55.6%; 95% CI, 51.4%–59.8%) were aware that screening recommendations had changed; however, 74.1% (95% CI, 70.3%–77.7%) still believed that women should be screened annually.23 By contrast, participants in the HPV FOCAL trial, who were able to learn more about HPV-based screening, were surveyed about their willingness to undergo primary HPV testing rather than Pap testing at the conclusion of the trial.24 Of the participants, 63% were comfortable with primary HPV testing, and 54% were accepting of an extended screening interval of 4 to 5 years.24
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