Analysis of False‐Negative Cancer Cases Identified with a Mammography Audit

▪ Abstract: The purpose of this study was to analyze the causes of false‐negative breast imaging in symptomatic and asymptomatic patients, as defined by cancer diagnosed within 1 year of a nonsuspicious mammogram. A computerized audit of 27,305 mammograms performed between November 1992 and December 1993 identified 50 patients who developed malignancy within 1 year of a mammographic report indicating negative, benign, or probably benign results. The audit revealed 26,661 mammograms interpreted as negative, benign, or probably benign. Of these, 50 patients were diagnosed with carcinoma within 1 year. Thirteen of the cancers were not visible retrospectively. Five were seen only in retrospect. Thirty‐two were seen prospectively, of which 5 were interpreted as benign and 27 were interpreted as probably benign. Seventeen of the 27 probably benign were recommended for 6‐month follow‐up. Ten of the 27 probably benign had immediate ultrasound‐guided fine needle aspiration cytology yielding unsuspected malignancy. In most (32/50) false‐negative cases the lesions were seen prospectively but were interpreted as benign or probably benign. Ultrasound‐guided aspiration averted a delayed diagnosis of malignancy in 20% (10/50) of the false‐negative imaging interpretations. Six‐month follow‐up studies were helpful for 12 of 17 cases, where the lesions progressed within 1 year. ▪