Zervixkarzinom-Screening

Abstract

Despite the undisputed and impressive success which has been achieved since the 1960s by cervical cytology in the fight against cervical cancer and its precursor stages, during which the mortality rate in industrialized countries over the last 40 years has been reduced by two-thirds to three-quarters, a perfect and error-free screening procedure is still a long way off and will probably never be reached. There are two main reasons for this, the lack of adequate coverage and suboptimal quality and assessment of smears. Two screening procedures are in use Europe, an opportunistic and an organized system. Both systems have many advantages but also disadvantages. In organized programs the coverage is higher (up to 80%), although similar numbers are also achieved by non-organized programs over a 3-year cycle, even if they cannot be so exactly documented. The decision on which system is used depends on the health system of the country, public or non-public, and many other national circumstances. However, in both systems prerequisites for a satisfactory result is a high quality in the sampling technique, the processing and the assessment. Therefore, several guidelines have been introduced by state and medical societies for internal and external quality assurance. New technologies, such as thin-layer cytology or automation for replacement or support of conventional cytology liquid-based cytology proved not to be superior enough to justify the high costs of these systems. The recognition of the strong causal relationship between persistent infection with high-risk human papillomavirus (HPV) types and cervical cancer and its precursors has resulted in the development of comparably simple tests. Primary screening using HPV typing alone is not recommended in opportunistic screening due to the low specificity but high sensitivity because it leads to many clinically irrelevant results which place women under stress. In organized screening HPV testing is always and only possible in combination with cytology. Various models and approaches are in the testing phase and appear promising. HPV testing is on the other hand well accepted and recommended as a triage test to select women with equivocal smear results (Pap group III, ASCUS) if a biopsy is required or can be followed up and also for follow-up of patients after cone biopsy. However, vaccination of young girls against oncogenic HPV types which has now become widespread still leaves many questions open for the future because the observation period is too short. There is justified hope that this will become a valuable tool in cervical cancer control and may lead to a substantial reduction in the burden of cervical cancer in the future. However, as the current vaccines on the market do not cover all oncogenic virus types and the effects of vaccination will only be observed after many years, the necessity of a cytological screening will remain unrestricted. Therefore, cervical cytology will remain as the trusted, simple to use, economic and proven, like no other method for early cancer detection, efficient procedure even in the foreseeable future. If carried out with the highest quality demands it will play a central role in the early detection of cervical cancer.