EGFR in triple negative breast carcinoma: significance of protein expression and high gene copy number
Abstract
BACKGROUND: As up to 60 % of triple negative breast carcinomas are reported to express EGFR, the receptor is a potential target for biological therapy. The exact role EGFR plays in triple negative breast carcinoma (TNBC) biology, however, remains uncertain.
We aimed to discover associations between EGFR protein expression as well as gene copy number changes and clinico-pathologic TNBC characteristics. METHODS: We performed an immunohistochemical and dual in situ hybridization study on a set of 52 archive cases of pre-treatment TNBC in order to detect EGFR protein expression and EGFR gene copy number changes.
Clinico-pathologic and follow up data were compared with EGFR status for determining possible links between EGFR and tumor characteristics and/or behavior. RESULTS: 88.5 % of our cases showed EGFR expression.
We found no significant links between EGFR expression and tumor grade (p = 0.204), lymph node status (p = 0.514) or p53 status (p = 0.078). Though EGFR gene amplification (EGFR gene:chromosome 7 ratio 2) was rare (1.9 % of all cases), a high gene copy number ( 4 copies per cell) was observed in 15.4 % of all cases.
High EGFR gene copy number appeared to be more common in non-ductal, special-type carcinomas than in ductal carcinomas. Neither EGFR expression nor EGFR gene copy number was associated with event-free survival.
CONCLUSION: EGFR changes do not appear to be associated with markers of aggressive behavior in TNBC. Further studies with much larger sample sizes are essential in understanding the role EGFR plays in TNBC biology in order to identify the patients that could benefit from EGFR targeted therapy.