To the Editor.—Pressman's recent letter about the delayed diagnosis of breast cancer as a result of a normal mammogram1 needs comment. Because of the glandular nature of the young breast and the dense shadows cast by chronic benign disease, the diagnosis of malignant neoplasm in these breasts is difficult to make. The cardinal rule is that a clinically suspicious lump must undergo biopsy despite mammographic findings. Obversely, a mammographically shown lesion suspected of being a malignant neoplasm must undergo biopsy, regardless of the clinical findings. If the clinician is aware of these problems, delay in the diagnosis of breast cancer due to mammographic findings need not occur. The primary function of mammography is to diagnose clinically occult cancer, and the secondary function, to give added information regarding a clinically suspected abnormality.
The state of the art in mammography has improved dramatically in the past few years, so that