The use of cervical screening history data to interpret cervical cancer incidence trends.

BACKGROUND Regional Cervical Screening Quality Assurance Reference Centres maintain and improve the quality of their local cervical screening programmes by monitoring standards based on a range of outcome measures. The classification of invasive cervical cancer screening histories can aid the interpretation of cervical cancer incidence trends in cervical screening services. METHODS Cervical cancer incidence rates were calculated for cytology laboratory catchment areas, which reflected where local general practitioners sent cervical samples. After reviewing changes in invasive cervical cancer incidence rates in the West Midlands during the period 1988-2004 to identify unusual trends, a detailed retrospective screening history analysis was carried out for one local screening service. RESULTS An upward trend in invasive cervical cancer incidence in one laboratory catchment area was caused by an increase in cases occurring in women who had not been routinely screened. Quality assurance data provided supporting evidence for non-attendance at screening during this time. CONCLUSIONS Assigning a screening status to invasive cervical cancers provides valuable information through which to understand the reasons for changes in cancer incidence with time in local screening services. These data can be used to identify areas of potential concern, thereby facilitating quality assurance activities.