Comparisons of different mammography techniques can be significantly altered by assumptions about the relevant measures for carcinogenic effects in mammography at low doses. Using a combination of recent data available from the literature, a study has been made of the significance of various assumptions concerning both the appropriate measures for carcinogenesis in mammography and the shape of the dose–effects relationship. It is found that for techniques typical of current reduced‐dose mammography systems, the comparison of the relative carcinogenic effects of the techniques is significantly affected by both the measures that are used and the shape of the dose–effects relationship.