The viral etiology of cervical cancer.

Epidemiological studies supported by molecular technology have provided sufficient 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. 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-deoxyribonucleic acid (DNA). This important advancement has two practical implications in prevention. Firstly, screening programs can be enhanced if HPV testing is judiciously incorporated into solving the fraction of ambiguous cytology readings. In some populations HPV screening as a primary test may prove to be the strategy of choice. Secondly, like in the hepatitis B disease model, intense efforts are currently being put into the development and testing of vaccines that may prevent the relevant HPV infections, and presumably, 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.