Technical optimisation of self-taken samples for improved cervical screening based on Human papillomavirus (HPV) testing

Abstract

HPV is a sexually transmitted infection infecting the majority of women at some point in their life. There are low and high risk types of HPV, and persistent infection with a high risk type may lead to cervical cancer. Vaccination programmes and cervical screening programmes have reduced the burden of HPV, however some women do not attend screening due to reasons such as fear, embarrassment or lack of time. To increase attendance, women may be offered the option to self-sample for HPV. Several countries have introduced self-sampling into their cervical screening programmes using vaginal swabs or brushes, whilst urine and tampon self-samples are under investigation. However, research into the optimum pre-analytical storage conditions for self-samples, and their influence on the assays used for analysis, are lacking.

This study investigated the optimal storage conditions for self-taken samples for HPV and assay specific differences in their analysis. Vaginal and urine self-samples were mimicked using an HPV 16 positive cell line and samples were stored between 4oC and 37oC for up to 30 weeks. Sample replicates were tested on various HPV assays at specific time points.

Vaginal self-sampling devices showed a decline in analytical stability when stored above 4oC for 12 weeks and tested on the Aptima assay, but all replicates tested positive on the Anyplex and Papilloplex assays regardless of storage temperature or time. Conservation medium appeared to prolong the stability of HPV in urine samples when stored for 4 weeks at room temperature. A systematic review and meta-analysis into the performance of self-taken tampons to detect HPV was performed and revealed a high level of concordance between tampons and clinician taken samples. A descriptive review was undertaken and showed that self-taken vaginal samples had similar invalidity rates to clinician taken samples and that increasing storage time may increase invalidity rates.

This research suggests that urine and tampon samples are viable methods of self-sampling for HPV and ought to be further considered for screening programmes. It is reported that vaginal self-samples give reliable detection of HPV even when stored at high temperatures for several months, although assay specific variations in analysis must be considered.