The relationship of cervical cytology to the incidence of invasive cervical cancer and mortality in Alameda County, California, 1960 to 1974.

Cervical cytology as an examination procedure is nearly ideal for discovering unsuspected cervical epithelial malignant changes. A large proportion of women is now being examined periodically with this procedure, and the question now is what effect has this had on the occurrence of invasive cervical cancer and deaths from this disease. Data are available on invasive cervical cancer and its mortality in Alameda County, California, for the 15 years, 1960-1974. Population survey data are available on the experience of women in the County with cervical cytology in 1962 and again in 1973-1974. All cases diagnosed in 1971-1975 were reviewed for a history of cytologic examinations in the 5 years prior to diagnosis. There has been a reduction of over 40% in the occurrence of invasive cervical cancer and mortality among white women in the 10 years 1960-1964 versus 1970-1974. There has been a lesser reduction in both among black women. Twenty-nine percent of women who developed invasive cervical cancer during 1970-1974 had a history of recent negative cytology. This finding indicates that not all invasive cervical cancers have a prolonged in situ stage.