Purpose: The basal-like phenotype has been found to be an independent poor prognostic factor for breast cancer. The aim of this study was to evaluate the association of WW domain-containing oxidoreductase (WWOX) expression with the basal-like subtype and clinicopathological parameters and to determine the prognostic significance of WWOX expression in patients with breast cancer.
Methods: Immunohistochemical analysis of WWOX expression was performed on 267 breast carcinoma samples, and then the mean value of WWOX expression was correlated to the basal-like status and clinicopathological parameters of the samples. The prognostic value of WWOX in primary breast cancer patients was determined for disease-free survival and overall survival.
Results: Expression of WWOX was negative in 29% of cases, and mean WWOX levels were significantly lower in basal-like breast cancers than in those of the non-basal-like subtype (P = 0.01). WWOX negativity was associated with decreased disease-free survival (DFS) (hazard ratio = 1.83; 95% CI, 1.01 to 3.28), but not with overall survival. Other tumor variables that showed a significant association with patient survival times included node status (hazard ratio = 0.38; 95% CI, 0.17 to 0.85) and breast cancer phenotype (hazard ratio = 0.36; 95% CI, 0.19 to 0.68). Multivariate regression analysis showed that lymph node involvement (hazard ratio = 0.43; 95% CI, 0.19 to 0.97) and basal-like subtype (hazard ratio = 0.33; 95% CI, 0.17 to 0.63) were also significant independent prognostic variables, and WWOX expression was of borderline significance for DFS (hazard ratio = 0.56; 95% CI, 0.31 to 1.03).
Conclusions: Reduced WWOX expression is associated with the basal-like subtype and a poor disease-free survival rate for breast cancer patients. Additional studies are warranted to better understand the role of WWOX expression, to further refine prognosis, and to optimize treatment in patients with basal-like breast cancer.