Elevated Interleukin-13 Receptor Alpha 1 Expression in Tumor Cells Is Associated with Poor Prognosis in Patients with Invasive Breast Cancer

Background: Interleukin (IL)-13 is an immunoregulatory, anti-inflammatory cytokine that is produced by numerous immune cells, and plasma membrane receptor for IL-13 (IL-13R) is known to be expressed in various human malignancies and in immune cells. Methods: The authors evaluated the expression of IL-13R alpha 1 (IL-13Rα1, an IL-13R subtype) by immunohistochemistry in tissue microarrays of 1213 invasive breast cancer (IBC) samples to determine the prognostic value of IL-13Rα1 expression. Results: High IL-13Rα1 expression was observed in 619 (51%) cases and was found to be associated with an older (≥50 years) age (p = 0.022), lymph node metastasis (p = 0.015), ductal and micropapillary histologic subtypes (p < 0.001), lymphovascular invasion (p = 0.012), HER2 positivity (p < 0.001), and a high (>20%) Ki-67 index (p = 0.039). No significant correlation was found between IL-13Rα1 expression and clinicopathological variables, including tumor size, histological grade, hormone receptor expressions, and tumor-infiltrating lymphocyte levels. Patients with high IL-13Rα1 expression showed poorer overall survival (p = 0.044) and disease-free survival (DFS, p = 0.001) than those with low/negative expression. Subgroup analysis revealed an association between IL-13Rα1 expression and survival for HER2-negative, but not for HER2-positive tumors. Multivariate analysis showed high IL-13Rα1 expression was an independent negative prognostic factor of DFS (p = 0.019). Conclusions: The results of this study suggest the IL-13 and IL-13Rα1 interaction promotes cancer cell growth and metastasis, and IL-13Rα1 expression is a potential prognostic marker in IBC.