NEW YORK (Reuters Health) – Primary HPV testing is better than cytology for detecting high-grade precancerous cervical lesions, according to results from the Compass trial in Australia.
“Compass is the first trial to compare HPV screening with cytology tests in a population with substantial uptake of the HPV vaccine,” Dr. Karen Canfell from Cancer Council New South Wales and University of Sydney, in Australia, told Reuters Health by email. “Our results . . . provide important initial confirmation that HPV screening will be better able to detect cervical precancerous lesions – not just in unvaccinated women, but also in younger cohorts who were offered the HPV vaccine.”
The Pap test (cervical cytology) has long been a mainstay of cervical screening around the world, and HPV screening has played an increasingly important role during the past decade.
The latest draft guideline from the U.S. Preventive Services Task Force recommends cytology screening every 3 years for women ages 21 to 29, either a Pap test every 3 years or an HPV test every 5 years for women ages 30 to 65, and no screening before age 21 or after age 65. (http://bit.ly/2h73xLJ)
Dr. Canfell and colleagues aimed to assess the rates of detecting cervical intraepithelial neoplasia grade 2+ (CIN 2+) in an open-label randomized trial of 5-yearly HPV screening versus 2.5-yearly cytology screening in Australia. Their findings were published online September 19 in PLoS Medicine.
Nearly 5,000 women ages 25 to 64 were randomized, in a 1:2:2 ratio, to three approaches:
– Liquid-based cytology screening with HPV triage testing of low-grade cytology (LBC screening);
– HPV screening, with partial genotyping and direct referral of women with detected HPV16/18 to colposcopy and with liquid-based cytology triage for other high-risk (OHR) oncogenic HPV types (HPV+LBC triage; equivalent to new screening recommendations in Australia);
– HPV screening with partial genotyping and direct referral of women with detected HPV16/18 to colposcopy and with dual-stained cytology triage testing for OHR oncogenic HPV types (HPV+DS triage).
In the LBC screening group, 0.1% of women had high-grade cytology and 6.6% had low-grade cytology; two-thirds of the latter subgroup was HPV-triage positive.
The overall observed HPV16/18 rate was 1.2% among HPV-screened women: 1.3% of the HPV+LBC group and 1.1% of the HPV+DS triage group. These groups’ OHR-positive rates were 5.5% and 6.0%, respectively.
Initial overall colposcopy referral rates – 2.7% in the LBC screening group, 3.8% in the HPV+LBC group, and 3.9% in the HPV+DS triage group – did not differ significantly after adjustment for HPV vaccination age eligibility.
Overall CIN2+ detection rates were significantly lower in the LBC screening group (0.1%) than in the 2 HPV-screened groups (roughly 1%).
Among women previously age-eligible for vaccination, the detected CIN2+ rates were 0.5% for LBC screening, 2.6% for HPV+LBC, and 2.9% for HPV+DS. Among older women, age-ineligible for vaccination, the rates were 0.0%, 0.6%, and 0.7%, respectively.
“Australia was the first country in the world to implement widespread HPV vaccination – 11 years ago in 2006 – and has achieved high levels of vaccine coverage,” Dr. Canfell said. “So it is the first country to experience a significant overlap between cohorts of women who had been offered vaccination and those eligible for cervical screening. Therefore, this trial has important implications for other countries, where eventually large numbers of women who have been vaccinated will also present for screening.”
“Our findings support a move to HPV screening in the new era of HPV vaccination,” she said. “We know that greater downstream protection against cervical cancer is provided by HPV screening, and this is the first indication that this will be true for a vaccinated population as well.”
“For population screening, we aim to identify those at highest risk so that they can be investigated further,” Dr. Canfell said. “No screening approach is perfect – but we can say with confidence that 5-yearly HPV-based screening looks to be extremely beneficial for women.”
“Our study was done in the context of the first-generation HPV vaccine (which protects against about 70% of cervical cancers),” she said. “The impact of the next-generation vaccine (protecting against about 90% of cervical cancers) – which has been approved in the U.S. and has recently been recommended for approval in Australia – might in the longer term have even further implications for cervical screening.”
Dr. Canfell concluded, “I’d like to reinforce the point that HPV-vaccinated women need to continue screening as well – while they are at a much lower risk of HPV infection and subsequent high-grade abnormalities or even cervical cancer, they too benefit from HPV screening.”
Jonah Musa, PhD candidate at Northwestern University, in Chicago who has published extensively on HPV and cervical cancer, told Reuters Health by email, “The results of this report should be followed by a cost-effectiveness analysis of the option of HPV testing as primary cervical cancer screening strategy in an HPV-vaccinated population.”
Like Dr. Canfell, he stressed emphasizing screening even in HPV-vaccinated populations.
SOURCE: http://bit.ly/2hgIEgX
PLoS Med 2017.
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