HPV based screening also results in fewer unnecessary colposcopies in tandem with an increase in HPV vaccination
(30th June @ 1600 hrs) An international study, with centres in Ireland, published today in JAMA NETWORK OPEN showed that molecular testing for human papilloma infection (HPV) infection, outperformed liquid-based cytology (LBC) approach, detecting 19% more true positives of CIN (cervical intraepithelial neoplasia). The study which sought to estimate the likely outcomes of different cervical screening modalities and to model how the increasing uptake of HPV vaccination could affect the interpretation of screening results, in a simulated population of 1000 women over 25 years of age, showed HPV test sensitivity at 89.9% and LBC test sensitivity at 75.5%.
The study showed that co-testing (using HPV and LBC testing) markedly reduced missed cases of CIN (cervical intraepithelial neoplasia), detecting 29% more true positives than LBC alone per 1000 women screened, but increased excess colposcopy referral by 94%. By contrast, triage testing with reflex LBC testing of HPV positive cases reduced false positives by a factor of approximately 10. The study also showed that where there was 80% vaccine coverage, HPV testing resulted in 44% excess colposcopies and with 80% vaccine coverage, LBC testing resulted in 96% excess colposcopies. The study concluded that over a lifetime of screening, reflex approaches with appropriate test intervals maximised treatment efficacy and as HPV vaccination rates increased, HPV-screening approaches resulted in fewer unnecessary colposcopies than LBC approaches.
Speaking about this study (which was based out of the School of Physical Sciences, DCU) Donal Brennan, Prof of Gynaecological Oncology, UCD and Consultant Gynaecological Oncologist, Mater and St Vincent’s University Hospitals, Dublin and one of this study’s co-authors said ‘Cervical screening, with its’ array of approaches, is a life-saving intervention, delivering an estimated 80% reduction in mortality. The evolution of cervical cancer screening to include HPV testing has also been very welcome. But any screening for cervical cancer has to be applied carefully to have maximum benefit, while minimising consequences of overtreatment in false-positive cases. This study confirmed that over screening or using screening modalities that are inappropriate to the target population may cause significant harm, including overtreatment.’
‘Essentially this study confirms that future of screening must be considered as HPV vaccination is already reducing the prevalence of cervical cancer globally. For example, modelling studies in Australia suggest HPV vaccination could virtually eliminate cervical cancer in coming decades. But as rates of cervical cancer decrease, the proportion of false positives via screening will increase so it is crucial we quantify this to deliver the optimal cervical screening approach, as this shapes the interpretation of results and clinical judgement’ continued Prof Brennan.
In this decision analytical model, the effectiveness of cervical cancer screening changed with prevalence of population-level HPV vaccination in addition to the effective sensitivity and specificity of the selected testing modality. This analysis should prove useful in optimising approaches and demonstrating complexities of different implementation so that informed decisions can be made. The balance of benefits and harms from screening will decrease in parallel with the decrease in cervical lesion prevalence, which will lead to rethinking with regard to test characteristics (age at start, age at exit and frequency of screening.)
ENDS