Prognostic Significance of Low Claudin3 Expression in Luminal Breast Cancers.

Aim: To study the prognostic value of immunohistochemically detected low Claudin3 expression in breast cancers.

Methods: This retrospective study included patients with breast cancer who were investigated at our unit from 2006 to 2015. Tissue microarrays were constructed, and immunohistochemical staining was done to assess the Claudin3 expression and to classify breast cancers according to the immunohistochemical surrogates for molecular classification. Kaplan-Meier model and log-rank test were used for recurrence-free survival and breast cancer-specific survival analysis.

Results: Of the 853 patients, overall low expression of Claudin3 was seen in 18.4%. Recurrence-free survival of patients with overall low Claudin3 breast cancers was poor in luminal A ( P  = .006) and luminal B (Her2-) ( P  = .009) subtypes compared with those who had Claudin3 expression in each group.

Conclusions: Assessment of Claudin3 expression by immunohistochemistry is suggested for luminal A and luminal B (Her2-) subtypes to identify patients with poor prognosis.