17 June 2019

Positive early findings from HPV screening

Clinical Women

Three times as many women are being referred for colposcopy after having a HPV test compared with the biennial pap test, researchers say.

A retrospective study, recently published in the MJA, found that women who had undergone the screening HPV test were more likely to be referred to colposcopy (2.6%) compared with women who had been screened with the Pap test (0.8%).

The researchers analysed the results of almost 200 000 HPV tests which were submitted to a Sydney-based pathology company for six months after the start of the renewed national cervical screening program.

The results indicated that women older than 30, who were more likely to be unvaccinated against HPV, were at a higher risk of testing positive for one of the 14 strains of HPV detected in the test.

“In 8% of primary screening tests and 21% of non-screening tests the samples were positive for oncogenic HPV. The prevalence of oncogenic HPV types other than HPV16/18 declined sharply with age, whereas that of HPV16/18 was low and similar across age groups,” the study authors said.

Associate Professor Annabelle Farnsworth, co-author and medical director at Douglass Hanly Moir Pathology in Sydney, said the study confirmed an age-specific pattern in the detection of oncogenic HPV which was leading to increased referrals to colposcopy testing under the new program.

“The rate of referral [to colposcopy] is huge, it’s about three times the rate of referral compared to the old program. That has put a lot of colposcopy services under a great deal of pressure, but somehow everyone is managing,” she said.

According to the study authors, the high rate of referrals to colposcopy was anticipated in the early stages of the new screening program as HPV-screening is more sensitive than cytology screening. However, as more vaccinated women enter the program it is expected colposcopy rates will decline in the future.

The findings from the study were consistent with previous studies from the National Cancer Screening Register which found that almost one in 10 Australian women tested positive for one of the 14 HPV types when screened under the new program.

But reassuringly, less than 2% of these cases were confirmed as one of the highly oncogenic HPV types 16 and 18 which are responsible for four in five cervical cancers in Australia.

In addition, the study found that women, for whom the referring doctor had requested co-testing with both the HPV test and cytology, were three times as likely to test positive for an oncogenic HPV strain, despite some anecdotal criticism that GPs may be over-ordering co-tests.

HPV co-testing with liquid-based cytology is recommended for all women, regardless of age, who have been treated for a high-grade abnormality in the past or who present with suspicious symptoms or signs.

“I don’t think the GPs are over ordering co-testing, I think it’s being used appropriately,” Professor Farnsworth said.

Overall, the study confirms that the renewed cervical screening program is performing as expected, however the authors say, ongoing monitoring is vital to ensure its success into the future.

“While the predicted long-term benefits are substantial, timely monitoring of the transitional phase is critical for ensuring the program performs as expected and community confidence in the policy is maintained,” the authors concluded.

MJA 2019, 10 June