Molecular subtypes of breast cancers detected in mammography screening and outside of screening.

Authors' Affiliations: Laboratory of Molecular Oncology, Biomedicum; Departments of Oncology and Obstetrics and Gynecology, Helsinki University Central Hospital. PURPOSE: The frequency and significance of gene expression profile-derived molecular subtypes of breast cancers found in mammography screening are unknown. EXPERIMENTAL DESIGN: We identified breast cancers diagnosed in women of any age living in defined geographic regions in Finland in 1991 to 1992 and collected clinical and pathologic data. Surrogates for the molecular subtypes were determined for 247 cancers found in organized mammography screening and 989 cancers detected outside of screening using immunohistochemistry or in situ hybridization. Molecular subtypes were defined as luminal A [estrogen receptor (ER) positive and/or progesterone receptor (PR) positive,... [read full story]