P1-01-14: Gene Expression of Immune Mediators within Nipple Aspirate Fluid and Ductal Lavage from Normal and Cancerous Breasts.

Abstract

Abstract The majority of breast cancers are thought to initiate in the lining of the 6 to 8 ducts that exit the nipple. Evidence suggests that the presence of nipple aspirate fluid (NAF), and in particular NAF containing atypical epithelial cells, in the ducts is predictive of future breast cancer risk. Although NAF fluid and cells may be representative of a preneoplastic state, use of NAF has not proven to represent a robust indicator for future malignancy. Chronic infiltration of tissues by immune cells predisposes them to future malignancy. Since macrophages can represent up to half of the total cells recovered from NAF, and their presence within malignant breast tumors has predictive value in terms of survival, we hypothesized that changes in the inflammatory microenvironment of breast ducts may foster future malignancy and/or provide an early indicator of future neoplasia. To test this hypothesis, we conducted an exploratory study to investigate gene expression in NAF and ductal lavage fluid. We first used real-time PCR to quantitatively measure mRNA expression of select genes within the cellular milieu of NAF to determine if that microenvironment correlated with a tumor-promoting state. Expression of multiple genes was observed in 15 samples collected from healthy volunteers, with robust expression of myeloid-associated genes including CD14, CD68, CCL3, CSF1 and IL1B observed in the majority of samples. To determine whether similar inflammatory microenvironments were found within each duct, and whether they were comparable to those in NAF-containing ducts, ductal lavage (DL) samples were obtained from 4 different ducts at the same time as NAF collection. Out of 7 volunteers, 4 provided samples allowing comparison between NAF and DL, and between multiple ducts. Analysis of gene expression from these healthy volunteers indicated that gene expression differed between NAF samples and each DL sample. More importantly, unique gene expression was found for each duct sampled, indicating that the immune microenvironment within each duct is distinct from other ducts within the same breast. In order to identify a potential inflammatory gene signature, we then obtained NAF samples from patients with breast cancer that had not received neoadjuvant chemotherapy prior to surgery, from both the cancerous and contralateral breasts. With 4 patients analyzed, no consistent expression difference has thus far been observed, indicating either that the relevant genes have not been identified, or that analysis of inflammatory genes within NAF may not be a predictive method with which to evaluate risk of future malignancy in women that produce NAF. A larger study is warranted to further investigate the significance of inflammatory gene expression in breast ductal fluid. Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P1-01-14.