353P - The Prognostic Meaning of Protein Tyrosine Phosphatase Non-Receptor Type 12 (PTPN 12) Expression Loss in Breast Cancer Patients

Abstract

ABSTRACT Background Recent preclinical studies showed that protein tyrosine phosphatase non-receptor type 12 (PTPN 12) appears to be an important tumor suppressor in breast cancer. However, the clinical and prognostic significance of PTPN 12 expression in breast cancer patients has not been elucidated yet. Methods PTPN 12 expression status was assessed for 183 patients who underwent curative surgery for operable breast cancer between May 2000 and August 2003, using immunohistochemical (IHC) assay of tissue microarray. Clinicopathologic characteristics, and expression status of ER, PR, EGFR, HER-2 were compared according to PTPN 12 expression status. The prognostic significance of PTPN 12 expression on disease-free survival (DFS) and overall survival (OS) was analyzed and the prognosis was also assessed in subgroups defined on the basis of major prognostic factors and ER, PR, HER-2, EGFR expression status. Results Loss of PTPN 12 expression was observed in 35.5% of the patients in this study. No significant differences were found in the clinicopathological characteristics and ER, PR, HER-2, EGFR expression status between PTPN 12 loss versus PTPN 12 intact patients. At a median follow-up of 9.9 years (range, 0.7-11.1), patients with PTPN 12 loss showed worse 10-year DFS than those with intact PTPN 12 expression (74.8% vs. 83.1%), but without statistical significance (p = 0.220). Ten-year overall survival of patients was not different according to PTPN 12 expression status. In the subgroup analysis performed in HER2 (-) and EGFR (-) patients (n = 128), the DFS was shorter in patients with PTPN 12 loss in univariate analysis (p = 0.057), and the difference was independently significant in multivariate analysis (hazard ratio, 2.97; 95% confidence interval, 1.05-8.37; p = 0.040). In the subgroup of patients who received hormone therapy alone as adjuvant treatment (n = 28), all recurrences were occurred in patients with PTPN 12 loss (5 recurrence in 16 patients) whereas there was no recurrence in patients with intact PTPN 12 expression. Conclusion PTPN 12 expression loss was associated to poor disease free survival in HER2 negative and EGFR negative breast cancer patients in this study. Our finding suggests that PTPN 12 may have a prognostic meaning predicting recurrence in HER2 negative and EGFR negative breast cancer patients, and future validation is warranted. Disclosure All authors have declared no conflicts of interest.