Risk of cervical cancer among an electrocoagulated population.

In Finland an organized mass screening program covers the total female population. Based on the material (429,832) from a nationwide mass screening registry it was estimated that the female population not subjected to electrocoagulation of the uterine cervix (362,511) had a sixfold risk of frankly invasive carcinoma, a fourfold risk of carcinoma in situ or dysplasia of high degree, and a twofold risk of dysplasia of low degree as compared with the female population subjected to electrocoagulation of the uterine cervix (67,321). The relative risk of cervical lesion varied by cytologic diagnosis, marital status, and Trichomonas vaginalis.

Effect of a mass screening program on the risk of cervical cancer.

In Finland, the organized mass screening program for the early detection of cervical cancer covers, with few exceptions, all women between the ages of 30 and 55 every fifth year. On the basis of material originating from the Finnish Cancer Registry it was estimated that the probability for a woman aged 30-59 to experience frankly invasive cervical cancer was 0.010 before the screening program, and 0.002 after the first screening. The corresponding probability estimate was 0.022 for pre-invasive lesions subjected to operative treatment. On the assumption that the same relationship applies beyond this age group it was estimated that from 28-39% of the pre-invasive cases progress to invasive cervical cancer, and that 21% of the frankly invasive cases are preceded by a pre-invasive stage of shorter duration than the time period between the screenings, or have no preclinical stage.

Mass screenings for cervical cancer in Finland 1963-71. Organization, extent, and epidemiological implications.

In Finland, up to 100,000 smears are taken annually from Finnish women, who number more than 2 millions, in conjunction with the mass screening programme organized by the Cancer Society of Finland. About 400,000 smears were taken during the period 1963-71; the detection rates per 10(5) were found to be 69 for invasive cancer, 6 for microinvasive carcinoma, 168 for carcinoma in situ, 127 for dysplasia of high degree. Those previously married, and those experiencing bleeding on sexual intercourse, formed high risk groups (relative risk 2 and 6) whereas those previously electro-coagulated had a relative risk of 0.13 only. Probably no changes will occur in the time trends of mortality rates as a result of the screening. The incidence of invasive carcinomas was found to be decreasing by time, although the increase in carconoma in situ cases exceeded this decline.