Effect of cytologic screening on the detection of cervical carcinoma.

An investigation has been made of the relationship between the histologic features of detected cancers of the uterine cervix and the history of previous cervical screening in 732 cases. Six hundred forty-nine of 732 (88.7%) cases with cancers of the uterine cervix were from the group of unscreened women. Frank invasive carcinoma was found in 21.0% (136 cases) of the former group and in only 3.6% (3 cases) of the latter. Adenocarcinoma of the uterine cervix was found in 0.3% (21 cases) of the unscreened women and in 7.2% (6 cases) of the screened women. Among the women who had undergone cervical screening within 3 years prior to a histologically confirmed diagnosis, invasive carcinoma (excluding adenocarcinoma) was found in 23.3% (14 of 60 women), whereas carcinoma in situ was found in 76.7%. This ratio (1:4) of invasive carcinoma to carcinoma in situ was found to be unchanged among the women of this group regardless of whether the interval from the previous screening was 1, 2, or 3 years. In contrast, when the interval between screenings was 4 or more years, the ratio of invasive carcinoma increased to 52.9% (9 of 17 cases).