It is now possible to screen for human papillomavirus which is the culprit for pre-malignant and malignant conditions of the cervix. This has only recently become available for clinical practice although it has been under investigation for more than ten years. There has been scepticism about the clinical value of HPV testing particularly on the part of those who may be required to provide funding. Studies indicate that when the HPV test is positive there is a 50% chance that there will be a high grade of CIN.
Those responsible for funding healthcare perceive an additional expenditure should HPV testing be widely adopted. They point out that 20% of young women are likely to be infected with the virus but the majority will not go on to develop pre-malignancy.
About 1-2% of smears are reported to be unsatisfactory and a repeat test is re quested by the laboratory. This causes stress for the patient who assumes that there is a major problem. It has been estimated that the annual cost of repeat smears in the USA amounts to $3 billion. Those with experience of combined cytological and HPV testing suggest that the referral rate for colposcopy may be reduced by 30%. They also suggest that, from an economic point of view, the combination of cytology and HPV testing results in a cost reduction. In Switzerland, there has been a 10% reduction in the overall cost of screening since the introduction of HPV testing. In the UK it has been estimated that the worst scenario of introducing routine HPV screening in conjunction with PAP test (cervical smear)s would be a neutral effect on funding but there could be a ?30 million saving.
In the UK 5.5million smears are taken annually. It would seem that if the combination (PAP test (cervical smear) and HPV test) results in fewer false negative results and less unnecessary intervention, HPV testing would prove to be cost-effective. The value to the patient of better reassurance that she is having more effective screening cannot be measured.
Currently PAP test (cervical smear)s are usually read by trained technicians. A typical slide sent by the doctor will include about 30,000 cervical cells. Large numbers of cells are assessed under low power microscopy and the majority of cells are evaluated. Abnormal cells are more obvious under higher magnification but time precludes checking all the cells. Computer systems such as Papnet are under investigation to see if they could improve accuracy.
One of the potential problems of introducing HPV testing is that perhaps 25% will prove positive potentially increasing the need for colposcopy manyfold.
The exact place of HPV testing has yet to be determined.
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