FIGURE 3-4 Mammographic sensitivity increases with a woman’s age.

screens, but a higher percentage of abnormal mammograms, biopsies, and false-positive findings. Therefore—if judged by rates of false positives—the apparent performance of a mammography service or individual radiologist would be influenced by the proportion of how many women are receiving their first mammogram.

A relationship between the volume of procedures performed and the outcome of those procedures has been established for many complex medical procedures, particularly in surgery and oncology.⁵⁵ Many studies have suggested that the volume of mammograms read by a radiologist is correlated with accuracy, and mammography volume standards are mandated by federal law. However, relatively few studies have directly compared the number of mammograms read by a radiologist and the accuracy of their interpretations. The results of these are variable, and are shown in Table 3-4. The most comprehensive study to date was the analysis by Beam and his colleagues in 2003,¹² which indicated that the volume of mammograms interpreted by a radiologist accounts for less than 2.5 percent of the variation. This means that more than 97 percent of inconsistency in interpretation is due to other factors.