IN A previous study by Humphrey and Swerdlow1 the finding of large duct epithelial hyperplasia in 69% of breasts removed for carcinoma was reported. A similar type of hyperplasia was also present in eight of 14 (64%) benign breast lesions excised 1 to 13 years before the development of carcinoma. On the other hand, only nine of 61 (16%) benign lesions that were diagnosed as fibrocystic disease and in which carcinoma did not develop were found to have large duct epithelial hyperplasia. This method of histologic examination as originally described2 stressed the importance of separating epithelial hyperplasia of large and small ducts.
With this strong correlation between large duct epithelial hyperplasia and carcinoma of the breast, a study was initiated to determine, if possible, the natural history of this specific histologic lesion.
From records and slides reviewed in the original study, there were 63 breast biopsies performed between 1946