Interleukin-13 receptor alpha 2 expression in tumor cells is associated with reduced disease-free survival in patients with luminal subtype invasive breast cancer.

Interleukin-13 receptor alpha 2 is one of the subunits of transmembrane receptor for interleukin-13. The aim of this study was to investigate the prognostic value of interleukin-13 receptor alpha 2 expression in invasive breast cancer. Interleukin-13 receptor alpha 2 expressions were assessed by immunohistochemistry in tissue microarrays of 1283 invasive breast cancer samples, and associations between these expressions and clinicopathological variables and clinical outcomes were investigated. Interleukin-13 receptor alpha 2 expression was observed in 138 (10.8%) samples, and found to be associated with positive estrogen receptor (p < 0.001) and progesterone receptor (p < 0.001) and with the luminal subtype (p < 0.001). No significant association was found between interleukin-13 receptor alpha 2 expression and other clinicopathological variables including age, tumor size, lymph node metastasis, histologic types, histologic grade, HER2 status, Ki-67 labeling index, or tumor-infiltrating lymphocytes levels. Patients with interleukin-13 receptor alpha 2 expression tended to have poorer disease-free survival, but the difference was not statistically significant (p = 0.069). Subgroup analysis showed luminal breast cancer patients positive for interleukin-13 receptor alpha 2 expression had significantly poorer disease-free survival (p = 0.018) than luminal breast cancer patients negative for interleukin-13 receptor alpha 2 expression. However, no association between interleukin-13 receptor alpha 2 expression and clinical outcome was observed in HER2-positive and triple-negative subgroups (p = 0.574 and p = 0.936, respectively). Multivariate analysis showed interleukin-13 receptor alpha 2 expression was an independent poor prognostic factor for luminal breast cancer (p = 0.03). This study shows interleukin-13 receptor alpha 2 expression could be a useful prognostic marker for selecting patients with luminal breast cancer likely to follow a clinically aggressive course despite receiving systemic therapy.