Routine audit of large-scale cervical cancer screening programs.

In this issue of the Journal, Andrae et al. (1) present the first audit of a national screening program for cervical cancer, and they should be congratulated for their efforts. In the United Kingdom, such audits were proposed in 1986 (2) and pilot audits were first reported in 1996 (3), but audits have yet to be translated into a routine national activity. Screening is a large-scale, repetitive " industrial process " and, as with all other such processes, one can learn most about its performance by examining the failures — here defined as a woman who is eligible for screening and who develops a potentially fatal cervical cancer — and then retuning the process accordingly. To this end, the screening histories of women who developed cervical cancer can be compared with those of a population-based age-matched sample of women who were eligible for screening but did not develop cancer. Three broad groups of screening failures can be identifi ed: 1) women who were not screened within the recommended interval; 2) women who were screened and found to have an abnormality, but who still subsequently developed cancer; and 3) women who were adequately screened within the recommended interval with apparently normal results, but who subsequently developed cancer. Each of these broad groups represents a different type of failure and indicates the need for a different sort of remedial action. The fi rst group of screening failures is a result of inadequate coverage and needs to be examined separately for women of screening age and for those beyond the recommended age for routine screening. For women younger than 65 years (5 years older than the age at which the last screen is recommended in Sweden), coverage within the recommended interval was reported by Andrae et al. (1) to be 68% for population-based control subjects but only 49% for subjects who were diagnosed with cervical cancer (case subjects), leading to an odds ratio of 2.21. Little difference in the protection afforded by screening was seen between women younger than 30 years and those aged 30 – 65 years. Not unexpectedly , the rates of screening within the past 5 years were much lower for women older than 65 years (ie, only 8% for case subjects and 19% for control subjects). The fact that 32% of all cancers — and an even greater percentage of late-stage tumors — appeared in this age group suggests …