ASSESSMENT OF LIFETIME GAINED AS A RESULT OF MAMMOGRAPHIC BREAST-CANCER SCREENING USING A COMPUTER-MODEL

A computer model for the simulation of breast cancer screening (MBS) i s used to calculate the results of screening in terms of lifetime. To optimize breast cancer screening protocols, risk (lifetime lost due to radiation-induced tumours) versus benefit (lifetime gained due to ear ly detection of breast cancer) analyses are performed for a simulated stable Swedish female population. The present study focuses on the res ults of different screening strategies employing single view mammograp hy, including starting and finishing ages of screening, time interval between successive screening sessions as well as the influence of high detection screening and differences between different populations, ba sed on lifetime lost or gained. To test the stability of the recommend ations with respect to possible changes in the variables used in MBS, calculations are also performed for high risk factors for breast tumou r induction using both the additive and multiplicative risk models, fa st growing breast tumours, late incidence of breast tumours and age de pendent survival. The results of the simulations expressed in terms of lifetime gained suggest that a theoretical benefit can be obtained em ploying starting and finishing ages of 35 and 75 years, respectively. In terms of number of fatal breast rumours, the favourable screening p eriod is 40-80 years. It is concluded that the recommendations are sta ble for changes in the input variables of MBS. The benefits of higher detection screening are more marked for younger than for older women. A high screening frequency results in more lifetime gained, especially al relatively young ages, whereas for older a es the effect is only m arginal.