The effects of timing of fine needle aspiration biopsies on gene expression profiles in breast cancers

Paired fine needle aspiration biopsies (FNABs) of breast cancers were taken before (PRE) and after (POST) surgeries from 16 patients and compared the cDNA microarray data to determine the genes that were differentially expressed between the FNABs taken at the two time points. The timing of fine needle aspiration biopsies can be a confounding factor in microarray data analyses in breast cancer. FOS-related genes, which have been implicated in early hypoxia as well as the development of breast cancers, were differentially expressed before and after surgery. Therefore, it is important that future studies take timing of tissue acquisition into account. Keywords: Breast cancer, fine needle, biopsy timing, microarray standardization, early hypoxic genes Dye-swap technical replicates were included both in PRE and POST FNABs for every patient, then the two replicated array data were combined for analysis.