Risk- and cost-benefit analyses of breast screening programs derived from absorbed dose measurements in The Netherlands.

Risk- and cost benefit analyses for breast screening programs are being performed, employing the risk-factors for induction of breast cancer from six extensive follow-up studies. For women of the age group above 35 years and for a risk period of 30 years after a 10-year latency period, a factor of extra cases of 20 X 10(-6) mGy-1 can be estimated. This factor is by coincidence the same as the factor estimated by the Committee on the Biological Effects of Ionizing Radiations and by United Nations Scientific Committee on the Effects of Atomic Radiation for women above 20 years, and would have been about a factor 2 lower for the category older than 35 years. Measurements are being performed in Dutch hospitals to determine the mean absorbed tissue dose. These doses vary from 0.6 to 4.4 mGy per radiograph. For a dose of 1 mGy per radiograph (which can easily be achieved) and yearly screening of women between 35 and 75 years, the risk of radiogenic breast cancer is about 1% of the natural incidence (85,000 per 10(6) women) in this group. A recommended frequency of screening has to be based on medical, social and financial considerations. The gain in woman years and in completely cured women is being estimated for screening with intervals of 12 instead of 24 months. This estimation is based on the frequencies of the tumour diameters after 12 and 24 months intervals and the survival percentages for these tumour diameters. The medical and social benefit is 1,520 years life-time and 69 more cases completely cured per 1,000 breast cancer patients. The financial profit of a completely cured instead of an ultimately fatal cancer can be roughly estimated at 55,000 guilders. In addition the costs per gained woman-year are about 5,000 guilders (1 US $ = 3.60 guilders). In consequence, the extra costs of annual additional rounds of mammographic screening are balanced by the benefit.