Abstract
BACKGROUND: Gene expression profile studies classify breast carcinomas according to the molecular profile
into 4 groups; Normal-like group, Luminal group, Basal group and HER-2 group. The basal group has aggressive
behavior and do not respond to either radiotherapy or chemotherapy. They express genes characteristic of
basal/myoepithelial (basal/ME) cells as high molecular-weight cytokeratins including CK5/6, CK14, and CK17.
They have high histologic grade, pushing (non-infiltrative) borders, large zones of geographic or comedo-type
necrosis, stromal lymphocytic infiltrates and scant stromal content.
AIM OF THE STUDY: The aim of this study was identification of breast carcinomas with basal phenotype
referred to South Egypt Cancer Institute, relation between the clinicopathologic characteristics of both basal and
non-basal phenotypes and relation of basal phenotypes with the available clinical follow up data of patients aiming
to find out how basal phenotype affect patients’ outcomes.
MATERIALS AND METHODS: Formalin-fixed paraffin-embedded blocks of 168 female patients diagnosed as
primary invasive breast carcinoma were obtained from the archives of the Surgical Pathology Laboratory, South
Egypt Cancer Institute, Assiut University between years 2008 and 2012. Using tissue microarray technique, tissue
cores from all specimens were immunostained with CK5/6 and CK14 to detect the basal group and other non-basal
groups.
RESULTS: 77 cases (45.6%) were positive for CK5/6 and 81 cases (47.9%) were positive for CK14. Accordingly,
81 cases (47.9%) were of basal phenotype (which was positive for CK5/6 or CK14 or both) corresponding to 66
cases (39%) of the other types and 21 cases (13.1%) were missed. There was significant association between the
basal phenotype and presence of lymphovascular invasion (p-value < 0.001), presence of necrosis (p-value <
0.001), infiltrative margin (p-value< 0.001), inflammatory stromal infiltrate (p-value= 0.006) and cytoplasmic
expression of CK5/6 (p-value= 0.014).
. No statistical significance was observed between the basal phenotype and overall survival (OS), disease-free
interval (DFI) or distant metastasis-free interval (DMFI).
CONCLUSION: Basal-like breast carcinomas (BLBCs) have some distinctive features as presence of
lymphovascular invasion (LVI), necrosis, infiltrative tumor margin and inflammatory stromal infiltrate. They
showed tendency to occur in older age group, to be of large tumor size and of moderate grade.