HPV screening is far more effective than Pap tests: results from world-first clinical trial
The Compass trial is the largest clinical trial in Australia and is providing early insight into the performance of the new cervical screening program
A new study by Cancer Council NSW and the Victorian Cytology Service (VCS Ltd.) has presented results from the first phase of Australia’s biggest clinical trial. The Compass trial looks at how effectively HPV screening detects high-grade cervical abnormalities in comparison to cytology (i.e. the Pap test). For the first time ever, the trial compares HPV screening with Pap tests in a population with substantial uptake of the HPV vaccine.
The findings come as Australia prepares to transition to a renewed National Cervical Screening Program, which, among other changes, will introduce primary HPV screening. The new system will come into place in December this year, so the study is a timely confirmation of just how effective the new program is expected to be – not just in unvaccinated women, but also in those who were offered the HPV vaccine.
“Our study of about 5,000 participants found that compared to Pap tests, HPV screening provides significantly increased detection of high-grade cervical abnormalities,” Professor Karen Canfell, Director of Research at Cancer Council NSW, said.
“We found that the HPV test was substantially more effective at picking up high-grade abnormalities compared to the Pap test.”
The increased detection of high-grade abnormalities of precancerous lesions (CIN2 or higher), and earlier treatment leads to longer term protection against the development of CIN3 and invasive cancer.
“This adds to existing evidence about how much more accurate and effective HPV screening is. We now have a superior method for detecting not just the virus that causes cervical cancer, but also high-grade abnormalities,” Prof Canfell said.
The new screening program has previously been estimated to lower cervical cancer incidence and mortality by at least 20 per cent – thanks to the more accurate, effective and safe test.
In its first phase (the results of which are presented in this study), the Compass trial recruited women aged 25-64 who attended a routine screening at 47 participating practices in Victoria, Australia. The women provided a cervical sample, and were then sent on the management pathway that will be put into place in Australia as part of the renewed National Cervical Screening Program this December.
“The results represent the first real-life demonstration of how the treatment pathways for primary HPV screening in HPV-vaccinated cohorts of women can work in practice,” Associate Professor Marion Saville, Executive Director at VCS Ltd. said.
The second phase of the Compass trial is currently recruiting. Its target is 121,000 participating women presenting for either routine screening or follow-up management, making it the largest clinical trial ever undertaken in Australia. The investigators have recently been able to open up recruitment to South Australian women while continuing recruitment in Victoria.
“Women residing in Victoria and South Australia aged 25 to 38 years are likely to be eligible to participate and can get more information on the trial’s website – compasstrial.org.au,” A/Prof Saville concluded.
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Media contact: Isabelle Dubach, Cancer Council NSW, T: (02) 9334 1872 M: 0401 524 321, firstname.lastname@example.org
Notes to editor
- This release is based on a paper by Cancer Council NSW and VCS Ltd. researchers, published in PLOS Medicine.
- The paper is entitled “Primary HPV vs. cytology for cervical screening in a population offered HPV vaccination: First findings from Compass, a randomised open-label trial”.
- Compass – an open-label randomised trial of 5-yearly HPV vs. 2.5-yearly liquid-based cytology (LBC) screening – is conducted jointly by Cancer Council NSW and VCS Ltd.
- LBC screening is the method that is used when analysing Pap smear test samples.
- No prior trials of primary HPV screening compared to cytology screening have been conducted in a population with substantial uptake of HPV vaccination.
- In the first phase of Compass, consenting women aged 25-64 presenting for routine screening at 47 primary practices in Victoria, Australia, provided a cervical sample.
- The aim of the analysis was to assess detected CIN2+ (precancerous lesions) in the baseline screening round, and to determine the rate of colposcopy referral in HPV screening.
At the lab, samples from about 5,000 women were randomly assigned to one of three possible test pathways:
- analysed with LBC, with an HPV test for samples that showed low grade abnormalities
- tested for HPV, with HPV 16/18 positive referred to colposcopy and other high risk types to LBC (as in the renewed screening program)
- tested for HPV, with HPV 16/18 positive referred to colposcopy and other high risk types to dual-stained cytology, a newer method that might be used in the future.
- The study found that compared to cytology (i.e. the Pap test analysis method), HPV screening is associated with significantly increased detection of high grade cervical precancerous lesions in a population with high uptake of HPV vaccination.
- For the LBC-screened group, the overall referral and detected rates of precancerous abnormalities were 2.7% and 0.1%, respectively.
- For HPV with LBC secondary testing, the overall referral and detected rates of precancerous abnormalities were 3.8% and 1.0%.
- For HPV with dual-stained cytology secondary testing, the overall referral and detected rates of precancerous abnormalities were 3.9% and 1.2%.