Medical audit of a rapid-throughput mammography screening practice: methodology and results of 27,114 examinations.

Medical audit results from the entire experience of a rapid-throughput mammography screening practice are presented, comprising 27,114 examinations conducted from April 1985 to September 1989. The authors screened a self-selected physician-referred population, almost 94% of whom were asymptomatic. Estimated sensitivity of initial mammography interpretation was 93.1% with a specificity of 94.2% and a positive predictive value of 10.0%. Biopsies prompted by screening yielded a diagnosis of malignancy in 32.1% of cases; 170 breast cancers were identified, 67.1% requiring mammographic needle localization. Median cancer size was 12 mm, the rate of axillary nodal metastasis was 11.0%, and the systemic metastasis rate was 1.2%. Of the cancers found, 76.5% were stage 0 or stage 1. Conducting a medical audit is the most convincing way to demonstrate the success of a mammography screening practice, thereby providing this important information for the benefit of screenees, referring physicians, third-party payers, and the personnel who perform the screening.