Analysis of cancers missed at screening mammography.

Analysis of 320 cancers found in a screened population between August 1985 and May 1990 revealed 77 cancers that were "missed" at screening mammography. The missed lesions consisted of cancers incorrectly diagnosed after mammography (false-negative results) but visible in retrospect (n = 19); cancers correctly diagnosed after mammography but visible in retrospect on an earlier mammogram (n = 47); and cancers that went undetected by the first of two readers (n = 11). Missed lesions were categorized according to type of miss, reason for the miss, breast density, lesion features, and lesion location. The missed lesion were compared with 121 cancers that were correctly diagnosed at screening mammography. The missed cancers occurred in women with denser breasts (P = .046), were less likely to demonstrate malignant microcalcifications, and were more likely to demonstrate a developing opacity as an indication of cancer (P = .005). An understanding of the characteristics of missed lesions may be a valuable aid in increasing the sensitivity of screening mammography.