Basal Cytokeratin and Epidermal Growth Factor Receptor Expression Are Not Predictive of Response to Platinum Based Therapy for Women with Triple Negative Breast Cancer.
Maureen Cioffi-Lavina, Judith Hurley, Merce Jorda, Gail R Walker, Carmen Gomez-Fernandez. University of Miami Jackson Memorial Hospital, FL; University of Miami, FL; University of Miami Hospitals, FL; Sylvester Comprehensive Cancer Center, Miami, FL
Background: Experimental data suggests that triple negative breast cancers (TNBC) may have increased sensitivity to platinum-based chemotherapy, particularly in BRCA1 mutation carriers, whose cancers cluster among the basal-like subtype defined by gene expression profiling. The most consistent immunophenotype seen in basal-like TNBC includes expression of basal cytokeratin (CK5/6) and/or epidermal growth factor receptor (EGFR). We investigated whether the expression of CK5/6 and/or EGFR could predict for response to neoadjuvant platinum based therapy in a cohort of patients with triple negative breast cancers.
Design: We reviewed 79 TNBC diagnosed between 1999 and 2009, treated with neoadjuvant docetaxel plus platinum salts, with a pathologic complete response rate (pCR) of 26.6 % (21of 79), as defined by the absence of invasive disease in the breast and axilla. Immunohistochemistry for CK5/6 (DAKO) and EGFR (DAKO) was performed in all cases using the LSAB method. Fisher's exact test was used to compare pCR rates by expression of CK5/6 and/or EGFR.
Results: The pCR rate of 26.6% did not vary significantly (p=0.418) by expression of at least CK5/6 or EGFR; i.e. pCR achieved in 5 (19.2%) of 26 TNBC positive for at least one of the markers was comparable to pCR achieved in 16 (30.2%) of 53 TNBC negative for both CK5/6 and EGFR.
Conclusions: Although the expression of basal cytokeratins and/or EGFR can be used to identify TNBC that have a basal-like phenotype, the expression of these markers alone is not sufficient to predict for response to platinum based chemotherapy.
Monday, February 28, 2011 1:00 PM
Poster Session II # 64, Monday Afternoon