Xeroradiography of the breast: overview of 21,057 consecutive cases.

Xeroradiography was performed on 21,057 new patients referred over a 5 1/2-year period. For purposes of analysis, mammograms reported as "benign" or "follow-up suggested" were considered negative and those reported as "suspicious" or "strongly suggestive of cancer" were considered positive. All patients were followed up for 12 months. After 6 months, 773 breast cancers were diagnosed. An additional 19 cancers were proved to exist during the 6-12-month period. The cancer rate increased progressively with age and ranged from 1.2% at age 30-39 years, to 4.5% at age 50-59 years, to 11.8% at age 70 years and over. Mammography had a sensitivity of 91.1%, a specificity of 89.9%, and a predictive value of 25.5%. Sensitivity increased with age, ranging from 78.5% at age 30-39 to 95.1% at age 70 and over. Predictive value increased dramatically with age, varying from 12.4% at age 30-39, to 28.4% at age 50-59, to 49.4% at age 70 years and over.