Cervical cancer screening aims to detect pre-cancerous lesions when curative treatment is still possible and before (invasive) cancer has developed.
Nordic countries were among the first to implement organized cervical cancer screening between the 1960 and 1970.
Today, many European countries have some form of cervical cancer screening. In some countries screening is opportunistic, indicating that women come on their own initiative for screening or that screening is offered by a physician when the women visits the clinic for other reasons.
In other countries, organized screening programs exist where women of certain ages are regularly invited for screening. Screening programs in European countries show considerable variation in both design and performance.
The variation in screening efforts is reflected in the cancer incidences. In countries with a well-organized screening program and high screening participation, cervical cancer incidence rates have shown a substantial decrease in the last decades of the 20th century. Currently, in those countries a disproportionally large number of cancer cases are observed in poorly screened and unscreened women. In countries that rely on opportunistic screening or that have a program with low screening participation, cervical cancer incidences have remained high and in some countries, have even increased.
Traditionally, screening is cytology-based using so-called PAP smears. A PAP smear involves the collection of cervical cells by a medical doctor or a trained nurse during a gynaecologic examination. Specialized laboratory personnel assess the smears for specific cellular (cytological) changes that may indicate the presence of (pre)cancer. Women with abnormal PAP smear are referred to a gynaecologist for further diagnostic evaluation and, if necessary, treatment. Because the proportion of abnormalities that are detected by a single PAP smear is only 50-75%, and performance varies across population, organized screening programs use short screening intervals, with the number of screening tests per woman ranging from 7 to over 40 in some countries.
As an alternative to cytology, HPV DNA testing has been rolled out or is currently being implemented in several European countries. The proportion of (pre-)cancerous lesions detected by HPV DNA testing is considerably higher than cytology (90-95%) and shows less variability across populations. Studies have shown that women who receive an HPV test have a lower incidence of high-grade precancerous abnormalities in the next screening round compared to women who receive cytology.
An important aspect of a successful screening program is to attain high screening participation. Currently, most cervical cancer cases are observed in poorly screened and unscreened women. To increase participation, “self-sampling” can be used. During self-sampling women collect their own vaginal sample. It is considered as a friendly and acceptable alternative to sampling by the physician. Several studies have indicated that self-sampling may be an effective way to reach marginalized/poorly screened populations.
More effective and efficient screening are important to achieve elimination of cervical cancer as a public health problem. Together these imply that screening resources should be directed to those most at risk. Current screening programs are using a one-size-fits-all approach. Risk-based screening could replace this one-size-fits-all strategy and will be an important step in the elimination of cervical cancer.