Statistical Analyses

Statistical analysis was performed with the SPSS statistical software program, version 22.0 (SPSS Inc., Chicago, IL, USA). Multivariate analyses were conducted using Cox regression analysis to evaluate the association between FAK expression (FAK positive vs. negative) in the BC samples and established prognostic factors such as age at diagnosis (<50 years vs. ≥50 years), tumor size (pT1 vs. ≥pT2), histological grade (grade 1 and 2 vs. grade 3), hormone receptor status (ER or PR immunoreactive score (IRS) 1 or higher vs. IRS 0) and HER2 status (HER2 3+ or HER2 2+ and Fish positive vs. HER2 0, 1+ and HER2 2+ and Fish negative). Ki-67 was divided in low (≤20% positive cells) and high (>20%). Death from BC or unrelated to BC, and metastasis or local relapse were documented. Metastasis-free survival (MFS) was defined as the time between surgery and diagnosis of metastasis. Disease-free survival (DFS) was defined as the time between the date of surgery and the date of loco-regional or metastatic recurrence, BC related death or lost follow-up. Overall survival (OS) was defined as time between the date of surgery and the date of death through any cause. The correlation between FAK and clinico-pathological parameters was assessed using chi-square statistics. Univariate and multivariate Cox regression analyses were performed. Survival rates were calculated by the Kaplan-Meier method and survival times were compared using the log-rank test. All p values were 2-sided. A p value of <0.05 was considered statistically significant. Since no correction for multiple testing was performed results are interpreted as explorative.