title: Basal cytokeratin expression in relation to biological factors in breast cancer.
abstract: The objective of this study was to determine the predictive impact of several established tumor biological markers and clinicopathological findings for basal-like carcinoma. Expression was determined by immunohistochemistry using antibodies to cytokeratins 5/6, 14, and 17, and the cases were divided into basal-like carcinoma and non basal-like carcinoma. These subgroups were compared in terms of biological markers (HER2, estrogen receptor, progesterone receptor, Ki-67, P-53, and P-glycoprotein) and clinicopathological behavior. Of the 49 basal-like carcinoma cases, 25(51.0%) were P-53-positive, whereas 100 (35.9%) of the 278 non basal-like carcinoma cases were P-53-positive. A high ratio of nuclear Ki-67 expression was detected in 39 (79.6%) of 49 basal-like carcinoma cases and was significantly more common than in non basal-like carcinoma cases (81/278, 29.1%). P-glycoprotein expression was identified in 29 (59.2%) of 49 basal-like carcinomas but only 85 (30.6%) of 278 non basal-like carcinomas. We observed high levels of P-53, Ki-67, and P-glycoprotein, with the reduction or loss of estrogen receptor, progesterone receptor, and HER2 being more obvious, in basal-like carcinomas than in non basal-like carcinomas. Our findings provide further evidence that basal-like carcinoma has different mechanisms of histogenesis.
authors.affiliation: Department of Pathology, Saitama Medical Center, Saitama Medical University, Kawagoe, Saitama 350-8550, Japan. hajime@saitama-med.ac.jp
authors.forename: Hajime
authors.initials: H
authors.lastname: Kuroda
authors.forename: Fumitaka
authors.initials: F
authors.lastname: Ishida
authors.forename: Maki
authors.initials: M
authors.lastname: Nakai
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Ohnisi
authors.forename: Shinji
authors.initials: S
authors.lastname: Itoyama