THE change from Pap smear tests to human papillomavirus (HPV) testing made by the National Cervical Screening Program in 2017 is resulting in earlier detection of potential cancer-causing infections, according to the authors of research published online today by the Medical Journal of Australia.
The switch from biennial cytological Pap testing of asymptomatic women aged 18–69 years, to 5-yearly primary HPV testing of women aged 25–74 years was a “major paradigm shift” according the researchers, led by Dr Dorothy Machalek from the Centre for Women’s Infectious Diseases at Melbourne’s Royal Women’s Hospital.
The NCSP Renewal program distinguishes between HPV specimens submitted for primary screening and those submitted for other indications (non-screening), requiring laboratories to classify all tests accordingly for Medicare billing purposes and for patient management. Women with non-screening tests are regarded as being at higher risk than other women because of their symptoms or signs or a prior cervical abnormality.
Machalek and colleagues conducted a retrospective review of 195 606 specimens submitted for HPV testing between December 2017 and 31 May 2018, to measure HPV testing patterns and rates of oncogenic HPV-positivity.
Oncogenic HPV was detected in 8.1% of screening tests and 20.9% of non-screening tests. Among oncogenic HPV-positive screening tests from women of recommended screening age (25–74 years), 35.5% also had a cytologic abnormality. The proportion of HPV16/18-positive samples with high-grade abnormality was 15.3%. For samples positive for other oncogenic HPV types, the proportion was 6.3%. Repeat HPV testing after 12 months was recommended for 5.4% and direct colposcopy for 2.6% of screened women aged 25–74 years.
“A key finding was that the rate of referral to colposcopy based on HPV primary screening sample results for women of recommended screening age (2.6%) was considerably higher than that based on historical primary cytology screening results from our laboratory (0.8%),” Machalek and colleagues wrote.
“The higher rate is broadly consistent with clinical trial data and predictions from modelling.
“The switch from cytology- to primary HPV-based screening in Australia will ensure cervical screening is evidence-based and best practice,” they concluded.
“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.”
- Cate Swannell