Prognostic value of mesothelin expression in patients with triple negative and HER2-positive breast cancers

Abstract Purpose Mesothelin is a cell surface glycoprotein that is overexpressed in various malignancies. Recent studies have revealed that mesothelin plays an oncogenic role in tumor growth and drug resistance through the Wnt/NF-κB/PI3K/Akt signaling pathways. Herein, the expression of mesothelin in HER2-positive and triple-negative breast cancer (TNBC) has been correlated with prognosis. Methods A total of 430 patients with breast cancer treated between 2006 and 2013 were retrospectively reviewed; of these, 123 cases were considered TNBC ( n = 71; 58%) or were positive for HER2 ( n = 52; 42%). Mesothelin expression was assessed by immunohistochemistry. Results Of the patients with TNBC, 30 (42.3%) were positive for mesothelin expression, compared to only two (3.8%) of the HER2-positive cases. As most HER2-positive tumors were negative for mesothelin staining, statistical analysis was not performed. Median overall survival (OS) was 70.1 months for patients with TNBC, whereas median OS was 70.1 months, in the mesothelin-positive group and 74.5 months in mesothelin-negative group, respectively. Strong correlation was seen between mesothelin expression and tumor grade in patients with TNBC ( P < 0.005). In a multivariable Cox proportional hazards model, mesothelin expression was not independently associated with OS in patients with TNBC. Conclusions Expression of mesothelin was observed in 42.3% of patients with TNBC and demonstrated a strong association with tumor grade. However, its expression was not correlated with prognosis.