Low Expression of Tyrosine-protein Phosphatase Nonreceptor Type 12 is Associated with Lymph Node Metastasis and Poor Prognosis in Operable Triple-negative Breast Cancer

Background: Low tyrosine-protein phosphatase nonreceptor type 12 (PTPN12) expression may be associatedwith breast cancer growth, proliferation, and metastasis. However, the prognostic value of PTPN12 in breastcancer has not been clearly identified. Patients and
Methods: 51 triple-negative breast cancer (TNBC) patientsand 83 non-TNBC patients with a histopathology diagnosis from October 2001 to September 2006 were includedin this study. Immunohistochemical staining for PTPN12 on tissue microarrays was conducted.
Results: HighPTPN12 expression was seen in 39.2% of TNBC and 60.2 % of non-TNBC cases. Low PTPN12 expressionwas associated with lymph node status (p = 0.002) and distant metastatic relapse (p = 0.002) in TNBC patients.Similarly, low PTPN12 expression in non-TNBC patients was significantly correlated with lymph node status(p = 0.002), stage (p = 0.002) and distant metastatic relapse (p = 0.039). The high PTPN12 expression group wasassociated with longer DFS and OS compared with low PTPN12 expression group only in TNBC cases (p =0.005, p = 0.015), according to univariate Cox regression analysis.
Conclusion: These findings provide evidencethat low expression of PTPN12 is associated with worse prognosis and may be used as a potential prognosticbiomarker in TNBC patients.