The Cardiff Cervical Cytology Study. Prevalence and epidemiology of cervical neoplasia.

The Cardiff Cervical Cytology Study showed a prevalence of carcinoma-in-situ that rose to a peak of 6.1/1000 in age group 35-44 and then decreased. Prevalence of microinvasive and occult invasive carcinoma rose to peaks of 1.8/1000 and 1.1/1000 respectively in age group 45-54 and then declined. Epidemiological analysis was based on comparison to three groups-dysplasia, carcinoma-in-situ and microinvasive carcinoma combined, and occult and clinical invasive carcinoma combined. For all groups prevalence increased with lower social class, was higher in widowed, divorced and separated women than in married women, and increased with decreasing age at first marriage and at first pregnancy and with increasing number of pregnancies. The magnitude of these association was remarkably similar for all three histological groups. Screening for cervical neoplasia is based on the belief that the various histological categories are part of a continuum, a spectrum of disease, and the existence of a common epidemiological pattern for the three histological groups is consistent with such a hypothesis.