The future of cervical screening

Advice not to subsidise newer cervical screening tests has angered experts but a new committee looking at the future of the national screening program will still consider their future role. Rada Rouse reports.

PATHOLOGISTS who have been pioneering the use of the latest cervical screening technologies in Australia have been frustrated by repeated efforts to attract government funding.

Years of discussions and meetings, but no action, have left them concerned that Australia now lags behind other developed nations and the lack of funding is forcing younger women to face unnecessary investigations.

The latest rebuff, they say, is shortsighted for another reason. Thanks to the HPV vaccine, Australia is facing a new era of primary prevention of cervical cancer, which will necessitate changes to screening programs.

Cytopathologist and screening quality assurance expert Dr Huw Llewellyn says the latest decision by the Medical Services Advisory Committee (MSAC) leaves the cervical screening sector with something of a “dog’s breakfast”.

“You have senior scientists saying, ‘Where do we go from here?’,” he says.

TRIAGE TEST

The Royal College of Pathologists of Australasia (RCPA) submitted the application to MSAC for Medicare funding of the Hybrid Capture II HPV DNA test. It would be used as a triage test for asymptomatic women with routine cytology-detected possible or definite low-grade squamous intraepithelial lesions (LSIL).

The committee found that, compared with repeat recall cytology at one year, HPV triage testing would be safe and effective, but not cost effective “in the Australian setting at the current price of HPV testing”.

Dr Llewellyn, who was the RCPA nominee advising MSAC, points out there is level 1 evidence supporting the use of HPV as a triage test. However, subsidising the test is not currently cost effective, he says, because to make it work every woman needs to have a sample taken, even though only a fraction will require triage.

“If you test only one in 10 women, you have to pay for the vials for the other nine,” he says.

Rejection of the HPV test application, however, was “delaying the inevitable”, with rival tests in the pipeline likely to lead to competitive price points, he says.

A number of observers say the commercial pressure to replace Pap smear with HPV testing is considerable, as the introduction of universal female HPV vaccination will eventually diminish the number of useful applications of the test.

“This is the window of opportunity for the manufacturers,” another RCPA cytology spokeswoman, Dr Gabriele Medley, comments.

She agrees it would be hard for MSAC to accept the HPV triage application without also having liquid-based cytology (LBC) in place.

“If you wanted to triage a woman with a possible low grade, or low grade, abnormality, that has had only a conventional Pap smear, the woman would have to go back to the doctor for another visit, and there’d be another cost to Medicare,” she said.

“LBC is the only logical platform from which to do triage testing – the two are inextricably bound together.”

MSAC found, in its recent consideration of an application for funding of LBC, that automated slide reading using the ThinPrep Imager system reduced the rate of unsatisfactory smears and detected at least as many CIN 2+ lesions as conventional cytology.

“However, it has a high cost-effectiveness ratio which appears to be unfavourable in the current Australian setting,” the committee decided.

VALUED PROGRAM

A champion of automated LBC, Professor Annabelle Farnsworth, director of GynaePath at Douglass Hanly Moir Pathology, told a recent cytopathology meeting that while the conventional Pap smear remained the only cervical screening test that received a Medicare rebate, an estimated 25% of all smears were now accompanied by a liquid-based sample.

“It’s interesting that women are prepared to pay an extra $40 every two years,” Professor Farnsworth says.

It’s a fact she says underlines how much women value the screening program.

Despite its use of “old technology” – the current screening program is one of the best in the world.

Since its inception in 1991, Australia’s program has halved the incidence and mortality of cervical cancer.

But despite its success, time might be running out for Pap smears as the most cost-effective screening test, which some say should open the door for newer tests.

A report, from a 2007 national roundtable involving the Federal Health Department and Cancer Council Australia, warned that HPV vaccination would reduce the current screening program’s cost effectiveness.

“When the vaccinated cohort enters the screening program, low-grade squamous intraepithelial lesions are expected to decline by around 20%, high-grade SIL by 40% for those vaccinated against HPV 16/18, and 50% for those vaccinated against 6/11/16/18,” the report says.

THREE-YEAR INTERVAL

Experts have been warning that Australia’s cervical screening practice – Pap smears every two years from age 18 to 69 – is no longer in line with scientific understanding of the natural history of HPV infection.

Gynaecological oncologist Professor Ian Hammond says we are already in a mess with our current screening program.

“In my opinion we are... over-screening, and over-investigating young women in particular,” he says. Most abnormalities in young sexually active women resolve within a couple of years and do not progress to cancer, he says.

The International Agency for Research on Cancer now recommends a three-year screening interval, Professor Hammond says.

“It’s been demonstrated in the UK that screening younger women has no effect on the incidence of cancer in young women,” Professor Hammond says.

In line with the evidence, the UK screening program recently moved to a three-year interval with women commencing screening at age 25, and then moving to five-yearly intervals at age 49.

Professor Hammond, a spokesman for the Royal Australian and New Zealand College of Obstetricians and Gynaecologists and former chair of an NHMRC screening guidelines review, said the college hoped that a proposed new review of the entire screening program would reconsider the place of LBC and HPV testing.

In fact, departmental bureaucrats have been telling meetings of medical professionals over the past two years that the objectives of the review – dubbed the “renewal” – would include appraisal of new technologies as well as assessment of screening age and intervals.

It is believed that the announcement of membership of a renewal steering committee is imminent and that it will take around 18 months to deliberate in what many observers see as an unenviable task.

As HPV experts wrote recently in an editorial in the Journal of the American Medical Association,¹ it is a challenging time to be a clinician or health planner dedicated to cervical cancer prevention.

“Even though an increasingly powerful set of prevention tools is available... using vaccination, cytology and HPV testing without careful planning would invite waste and... over-treatment.”

Reference

1. JAMA 2009; 302:1809-10