Ages and frequencies for cervical cancer screening.

A simple method of calculating the best ages for carrying out cervical cytology screening procedures is proposed. The argument is graphical, the outcomes are readily understood by visual and intuitive methods, but a computer program for assisting the calculations is constructed. Use of the method indicates that relatively high rates of screening should be employed in women over 45, and that routine screening in women under 30 years of age is likely to be ineffective in reducing mortality. The method predicts that, if we assume a negative error rate for the test of 0-2, and a natural history with a mean interval between detectability and incurability of about 6 years, a series of 10 tests deployed between 35 and 80 years in England and Wales should give a yield of 0-67 deaths saved per 1000 tests performed, and should be capable of saving about 77% of all deaths from cervical cancer in women who conform with the recommendation.