The human papillomaviruses (HPVs) and HPV DNA testing

Abstract

The fact that some viruses act as carcinogens has long since been known. Amongst these viruses are some genotypes of the Human Papillomaviruses (HPVs). HPV is most frequently associated with cervical cancer, that is, cancer of the cervix or neck of the uterus. In fact, 95-100% of all cervical cancers are caused by infection with HPV. HPV also causes a high proportion of other anogenital cancers. In 1995, the International Agency for Research on Cancer (IARC) concluded that HPV types 16 and 18 are carcinogenic to humans; HPV types 31 and 33 are probably carcinogenic to humans whilst some HPV types other than 16, 18, 31 and 33 are possibly carcinogenic to humans. This review focuses first on the structure, classification and genome of these particular viruses. Particular attention is given to those features that play a role in the carcinogenicity of particular HPV genotypes. Given the close association between HPV and cervical cancer, detecting the presence of HPV in a particular patient and more specifically, the presence of particular genotypes of HPV, may give an indication of the likelihood of progression to precancerous and cancerous changes in the cervix. In fact, there is much evidence that screening of women with both cytology and HPV DNA tests increases sensitivity for detection of Cervical Intraepithelial Neoplasia (CIN) 3 or cancer sufficiently to permit longer screening intervals than with cytology alone. However, it is important to realize that the presence of HPV does not mean that a woman has or will develop cervical disease. Thus, there is still a dilemma as regards the real utility of HPV DNA testing. Screening and diagnostic procedures for cervical cancer will be discussed in the second part of this review, with special emphasis on HPV DNA testing. The benefits of HPV DNA testing in specific situations will be highlighted, particularly in the case of a diagnosis of Atypical Squamous Cell of Undetermined Significance (ASCUS).