A new method for the classification of invasive cervical cancer screening histories.

Objectives: To examine the ability of existing classification systems to provide screening histories for invasive cervical cancers which can be used in the evaluation of the NHS Cervical Screening Programme (NHSCSP), and to provide the diagnostic route data item required for the National Cancer Data Set (NCDS).

Methods: The ability of existing classification systems to derive unique, consistent screening histories for a cohort of invasive cervical cancers diagnosed in the West Midlands region in the period 2000-03 was tested using two separate timelines for women on normal routine recall (usually 3 or 5 years) and those on early recall having had an inadequate, low-grade abnormal or negative smear.

Results: Neither of the existing classification systems was capable of adequately categorizing all invasive cervical cancers. An original classification system incorporating features from the existing systems was therefore developed. This system includes both a 'screening status' component that essentially describes the status of a woman's interaction with the NHSCSP at the time her cancer was diagnosed, and a 'screening history' component that describes the results of previous screening tests.

Conclusions: National adoption of this new screening histories classification system would provide a detailed, consistent, nationally comparable screening history for all invasive cervical cancers which can be used in the national and regional evaluation of the NHSCSP and in local audit by clinical teams supplemented by histology and colposcopy data. The classification categories could be collapsed down to provide the diagnostic route data item required for the NCDS.