Breast cancer and normal breast tissue samples to estimate the effect of contamination of breast cancer samples with normal breast tissue

PURPOSE: To estimate the effect of contamination with normal breast tissue for the development of gene signatures robust to pre-analytical conditions. METHODS: We evaluated the effect of contamination with normal breast tissue on gene signatures by comparing microarray profiles of breast cancer samples contaminated with increasing amounts of normal breast tissue. A set of 10 breast cancer samples were mixed with increasing amounts of 10 individual normal breast tissue samples. Samples were contaminated with 0, 10, 25, 50, 75, 80, 85, 90, 95 and 100 % of normal breast tissue, respectively.