[A simple mathematical model for a quantitative evaluation of mass screening for detection of cancer]

In Japan, where the mass screening of various cancer are actively pursued under the auspices of the Adult Health Promotion Act of the Japanese Government, the incidence rate of various cancers has been undergoing a drastic change since 1960. Cancers of stomach and uterine cervix, which had predominated, are decreasing steadily, whereas lung, colon and breast cancers are rapidly increasing. To provide therapeutic care on the basis of accurate data, the mass screening system must be re-evaluated so as to maintain its effectiveness and efficiency. For this purpose, a simple, deterministic model is proposed to measure the cost-effectiveness of the mass screening quantitatively. The effect of the screening is estimated by the net number of lives that have been saved by the screening, with the final result being shown as the cost require to save one life of a certain age and sex. The model, although only an approximation, fits all kinds of cancers by changing the parameters employed in the mathematical equation, and has been found useful for forecasting the results of future mass screenings for the detection of cancers in Japan.