Spontaneous screening for cervical cancer and diagnostic histories of incident cases

Cytologic and colposcopic histories of cases of invasive cervical cancer and cervical intraepithelial neoplasia grade III (CIN III) registered in Ravenna (northern Italy) between 1986 and 1990 were evaluated. During the 5 years prior to diagnosis, 10/49 invasive cancer patients and 25/61 CIN III patients had had at least one pap smear reported as negative. At the time of the most recent false-negative report, 9/10 and 17/25 of these cases had been recommended for a repeat smear within 2 to 6 months. Of the 9 patients with invasive cancer, 5 had also undergone an inconclusive colposcopy (with biopsy unperformed). Among invasive cancer patients aged under 50, half of incident cases (7/14) and most of those with some cytologic experience (7/8) had had a false-negative report; each of these patients (7/7) had been recommended for an early repeat smear. For invasive cancer patients as well as for CIN III patients, the suggested intervals for the early repeat were largely exceeded. Median delay in diagnosis was about 2 years. Although the frequency of negative reports recommending repeat smears within a few months was estimated to be some 10% of total screening patients, current concepts in cervical cytology suggest that cancer cases with such false-negative reports should be regarded as follow-up failures rather than laboratory errors. In fact, they passed quite unnoticed. In unplanned (spontaneous) cervical screening practice, sensitivity needs to be maximized, but even the occurrence of false-negative cases is not monitored. The present study points out what may result from such a contradiction.