The causal relation between human papillomavirus and cervical cancer

During the 1990s, epidemiological studies, supported by molecular technology, provided evidence on the causal role of some human papillomavirus (HPV) infections in the development of cervical cancer. This association has been evaluated under all proposed sets of causality criteria and endorsed by the scientific community and major review institutes. The finding is universally consistent, and to date there are no documented alternative hypotheses for the aetiology of cervical cancer. HPV has been proposed as the first ever identified, "necessary cause" of a human cancer. In practical terms, the concept of a necessary cause implies that cervical cancer does not and will not develop in the absence of the persistent presence of HPV DNA. Cervical cancer is still the second most common cancer in women worldwide, although it is a theoretically preventable disease. In developed parts of the world, and in populations where cytology based programmes are established, it would be beneficial to add HPV testing to the screening protocol. HPV testing was shown by several studies, including one randomised trial, to be of help in solving the ambiguous cases generated by cytology reading. In populations where cytology programmes are either not in place or are not efficient, HPV testing should now be considered and evaluated as an alternative test for primary screening. Prevention of exposure to high risk HPV types by vaccination may prove to be the most efficient and logistically feasible preventive intervention for cervical cancer. At this stage of development, regulatory agencies are requested to evaluate the scientific evidence and weigh its implications in relation to costs, public health investments, and policy. This is a subjective evaluation that could be guided by a careful description of the most relevant studies and findings.