Stability of a mammographic mass: a false sense of security.

The observation of growth rates of human breast cancers on serial mammography has afforded an opportunity to document the spectrum of the natural history of these tumors in vivo. Five breast carcinomas in four patients were seen on mammography as clinically occult masses at least 1 cm in diameter. These lesions did not change in size on follow-up xeromammography over a minimum of 2 and a maximum of 4.5 years from the original radiographic examination. Since it is common practice for radiologists to recommend a repeat examination in 3-12 months of nonpalable masses, architectural distortions, and asymmetric areas of increased density which may not have typical signs of malignancy, the lack of interval changes does not necessarily indicate a benign process.