Large population survey: strengths and limits. Methodology of the EDIFICE survey.

In France, mass screening for breast and colon cancer issupported by the French National Cancer Institute (INCa). In these nationwide screening campaigns, individuals aged between 50 and 74 years receive a personalized letter inviting them for a screening examination every 2 years. Prostate cancer screening is, however, still controversial and has not been included in the INCa recommendations so far. Research organizations are particularly interested in screening and indeed, several studies have been conducted in France and other countries to examine the different aspects of the subject. To provide actual benefits, screening should be undertaken on a regular scheduled basis. Therefore, several studies have assessed the factors influencing the participation rate of women in breast cancer screening in France (). The Institut National de Prévention et d'Education pour la Santé conducted one of these in 2005: the Baromètre Cancer (including 4046 individuals aged 15 years or older, interviewed by telephone) analysed beliefs and perceptions about cancer screening and studied attendance rates for breast, colon and prostate cancer (including scheduled screening). No previous survey has ever been conducted simultaneously among the general population and physicians with regard to individual and scheduled screening for breast cancer and colorectal cancer (CRC) or individual screening for prostate cancer. EDIFICE is thus the first large-scale survey to assess screening practices in France by analysing the targeted population on the one hand and the clinical practice of French general practitioners (GPs) on the other hand, using the 'mirror study' method to compare results. Two national surveys were conducted in 2005 and 2008. In 2005, only 22 geographical regions were included in the screening programme for CRC.