Cotesting, the practice of adding cytology to human papillomavirus (HPV) screening, offered little added benefit over HPV testing alone in the detection of precancer among women aged 25-65 years, according to a large longitudinal Canadian study published in JAMA Network Open.

The timing is notable as cervical cancer screening guidance in the US is beginning to incorporate home-based HPV self-collection for women with average risk. Although the current analysis evaluated clinician-collected samples rather than self-collected testing, it speaks directly to the underlying clinical question driving that shift: whether HPV testing alone provides sufficient long-term reassurance to stand on its own, without routinely adding cytology.

The findings, which were published in JAMA Network Open, add to growing evidence that cotesting may offer limited clinical value despite its common use in the US. Increasingly, data suggest that HPV testing alone provides comparable reassurance against future cervical precancer, raising the possibility that screening strategies could be simplified without compromising safety.

“A negative HPV test alone provides very strong reassurance against future cervical precancer, similar to the reassurance from a negative cotest,” lead author Anna Gottschlich, PhD, told Medscape Oncology. Gottschlich is a researcher at the Barbara Ann Karmanos Cancer Institute and an assistant professor of Oncology in the Wayne State University School of Medicine, both in Detroit.

Although the study used clinician-collected samples, Gottschlich noted that “self-collected HPV testing is an exciting development in cervical cancer screening,” with evidence showing comparable performance when validated assays are used.

In the new study of more than 8000 women, researchers found the cumulative incidence risk (CIR) of detecting cervical intraepithelial neoplasia grade 2 or greater (CIN2+) was 0.41% among women who tested negative for HPV regardless of cytology results. This was similar to the 0.37% CIR among those with negative cotest results (HPV negative and cytology normal). Both were lower than the 1.28% detection CIR observed with normal cytology alone. CIR reflects the risk of detecting CIN2+ in the follow-up period.

While this study focused on women aged 25-65 years, in the US, current guidelines support HPV-based screening strategies for women aged 30-65 years, including primary HPV testing or cotesting, making this the group for whom the findings are most directly relevant.

Previous trials have established that primary HPV screening is more sensitive than cytology alone. What has remained less clear is whether adding cytology meaningfully improves long-term reassurance after a negative HPV result. This analysis answered that question. It found that, with more than 10 years of follow-up, cotesting provided little additional reassurance beyond HPV testing alone.

The risk for cervical precancer detection 9 years after a negative HPV test (regardless of cytology results) was similar to the risk only 3 years after a normal cytology screen (regardless of HPV results), according to this study.

“Cytology is often recommended at 3-year intervals, thus we propose that those who were HPV-negative had an acceptably low risk of precancer detection over the entire follow-up period, as did those with a negative cotest, who had an even lower risk,” they wrote.

This cohort study (FOCAL-DECADE) was an extension of the HPV FOCAL trial, which found that primary HPV screening is more sensitive than cytology alone. This trial included women aged 25-65 years undergoing routine screening. Exclusion criteria included recent CIN2+ or cervical cancer, recent screening, pregnancy, immunosuppression, or absence of a cervix.

Women who entered long-term follow-up (FOCAL-DECADE) had a negative exit test at the end of HPV FOCAL — reflecting a population at low average risk at baseline. HPV FOCAL did not report participants’ screening results prior to entering the study, including whether they had previous abnormal cytology or HPV-positive results.

The FOCAL-DECADE study included both HPV testing and cytology for each participant. Results were analyzed to approximate how HPV testing alone, cotesting, and cytology alone would perform. Most participants were White (76.1%), followed by Asian (22.4%) and Indigenous (3.0%) individuals; the median age was 49 years.

The higher sensitivity of primary HPV testing, demonstrated in several trials such as HPV FOCAL, supports a shift toward HPV-based screening with longer intervals between tests, reflecting the strong reassurance provided by a negative HPV result. In that context, the current findings suggest that adding cytology to HPV screening offers little additional long-term benefit, raising questions about whether cotesting is necessary to maintain that level of reassurance.

“Evidence like this helps guideline groups evaluate whether screening strategies can be simplified while maintaining safety,” said Gottschlich. “For example, using a single HPV test instead of two different tests could simplify screening programs, reduce healthcare costs, and make results easier for clinicians and patients to interpret. These efficiencies could allow healthcare systems to focus more resources on reaching people who are at higher risk or who are not regularly screened, an important step toward reducing cervical cancer rates and supporting global efforts to eliminate the disease.”

Despite this growing evidence, cotesting remains widely used in the US.

“One factor sustaining cotesting is the use of HPV assays not approved for primary screening and that may be the only option available within some laboratory workflows,” George Sawaya, MD, said in an interview. Although adding cytology can increase sensitivity, the incremental benefit appears small, he noted, and must be weighed against the added complexity of dual testing.

Sawaya co-authored a 2024 analysis of US screening populations, with similar findings. They found that cotesting increased the number of tests and colposcopies, while detecting relatively few additional high-grade lesions compared with primary HPV screening, particularly in lower-risk populations.

Gottschlich said the findings like these may also help shift laboratory practices. 

“As more data continue to demonstrate the effectiveness of HPV-only screening, studies like ours may help encourage broader adoption of laboratory platforms and workflows that support primary HPV testing.”

Sawaya is the director of Zuckerberg San Francisco General Hospital and Trauma Center’s cervical dysplasia clinic and a professor of obstetrics and gynecology at the University of California, San Francisco. Both Sawaya and Gottschlich reported having no disclosures.