Level 2: Mid-level evidence
The addition of human papillomavirus (HPV) DNA testing to either conventional or liquid-based cytology has previously been shown to increase detection rates of high-grade cervical intraepithelial neoplasia. Evidence from a new randomized trial suggests that HPV DNA-based testing may reduce the rate of invasive cervical cancer compared with cytology (Lancet Oncol. 2010;11:249-257).
A total of 94,370 women aged 25-60 years were randomized in two phases to HPV testing plus liquid-based cytology vs. conventional cytology (phase 1), or HPV testing alone vs. conventional cytology (phase 2). In both phases, all women with abnormal cytology were referred for colposcopy. In addition, in phase 1, if cytology was normal, women aged 35-60 years with positive HPV test were referred for colposcopy, but women aged 25-34 years were referred to colposcopy only if HPV testing was positive on repeated testing (or if cytology became abnormal). In phase 2, all women with a positive HPV test were referred for colposcopy. A second round of cytology-only screening within three to five years was performed in 73% of the cytology groups and 72% of the DNA testing groups. The two phases were pooled for analysis.
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Similar rates of invasive cervical cancer were detected in both groups during the initial round of screening. Invasive cervical cancer was detected in seven women in the DNA testing groups and nine women in the cytology-only groups. However, the DNA testing groups had a significantly lower rate of invasive cancer detected during the second round of screening (0 vs. 0.027% [nine cases], P=0.004, number needed to screen [NNS] 3,700). The invasive cancer rate was also lower for DNA testing in a subgroup analysis of women aged 35-60 years (P=0.016, NNS 4,800), but not in younger women.
The strength of the conclusions is limited by the pooling of the data from the two phases, which had different protocols. It is therefore unclear whether the results apply to HPV DNA testing alone, the combination of HPV DNA testing and cytology, or both.
