The histological typing was generally done according to the WHO classification (ref 1). In the present data sets, the tumors were classified into the following three categories:
ductal = not otherwise
specified, includes the apocrine, the mixed mucinous, and the atypical medullary
lobular = infiltrating lobular carcinoma with variants
special = includes the tubular, medullary, cribriform, papillary, and pure mucinous carcinomas
Note 1: The histological parameters were determined by more than 50 pathologists at the respective pathology laboratories at the time of the diagnosis.
1. World Health Organization. Histological typing of breast tumours. 2 ed. Geneva, Switzerland: World Health Organization; 1981.