TTK is a favorable prognostic biomarker for triple-negative breast cancer survival

PURPOSE: Previous studies demonstrate that threonine and tyrosine kinase (TTK) is overexpressed in triple-negative breast cancer (TNBC), but there are conflicting results regarding its effect on TNBC survival. The purpose of this study was to assess the prognostic significance of TTK expression in primary TNBC. RESULTS: Of 169 consecutive cases eligible for this study, 164 included follow-up information. Cytoplasm and membrane TTK staining was observed in 99.4% of cases, while 5.9% displayed whole cell immunostaining. At a discriminating threshold of 55, elevated TTK expression was associated with prolonged disease free survival (DFS) (p < 0.001) and overall survival (OS) (p = 0.024) in primary TNBC and prolonged DFS in individual basal-like (p = 0.001) and non-basal-like (p = 0.001) TNBC subtypes. In addition, Cox regression analysis demonstrated that elevated TTK expression was an independent prognostic factor for DFS in TNBC (p < 0.001). METHODS: TTK expression of 169 samples was tested by immunohistochemistry (IHC). A receiver operating characteristic (ROC) curve was used to identify a cutpoint for TTK expression, which was analyzed for its association with patients' clinicopathological factors and survival using Chi-square, log-rank, and Cox regression analyses. CONCLUSIONS: TTK is a favorable prognostic biomarker associated with TNBC survival.