Association of expression of aquaporin 5 (AQP5) with prognosis in hormone-responsive early breast cancer patients.

Abstract

e11594 Background: Our previous study showed the association of AQP5 up-regulation with cancer proliferation and migration in hormone-responsive breast cancer cell lines (MCF-7) and with unfavorable prognosis in a small number of patients with breast cancer. Accordingly, we analyzed the prognostic impact of AQP5 expression in a number of patients with early breast cancer (EBC). Methods: We enrolled 447 patients who underwent operation for EBC between June 2003 and August 2008 and performed immunohistochemical (IHC) stain for AQP5 expression in tissue microarray (TMA) collected from tumor tissue. Two pathologists independently scored staining intensity (IS, 0 through3) and percentage of positive tumor cells (PC, 0 through 4) and categorized as negative (0 through 2), weak (3 through 5), and strong (6 or more) according to the sum. Results: The median age of patients was 49 years (range 23-82). 80 (17.9%) patients underwent breast conserving surgery and adjuvant chemotherapy was given to 406 (90.8%) patients. Among enrolled subjects, 298 (66.7%) were hormone-responsive, 64 (14.3%) for HER2 overexpressed, and 79 (17.7%) for triple negative EBC by ER, PgR, and HER2 expression. AQP5 expression (staining score >2) was observed in 267 (59.7%) patients including 123 (27.5%) overexpression (stating score >5). In univariate analysis, AQP5 overexpression was associated with survival in patients with hormone-responsive and HER2 overexpressed EBC. Moreover, multivariate survival analysis revealed that AQP5 overexpression was an independent prognostic marker for survival in patients EBC, which was prominent in patients with ER/PgR-positive tumor type. However, no difference in AQP5 expression was observed based on patient and tumor characteristics. Conclusions: Consistent with our previous study with breast cancer cell lines, AQP5 expression in tumor tissue can be considered as a prognostic marker in patients with EBC after curative operation.