STAT5A and breast cancer: Low levels of Nuc-Stat5a were associated with increased risk of breast cancer recurrence (TTR; log-rank, P = 0.003; n = 223; Figure 2A; univariate Weibull regression hazard ratio (HR) = 2.60 (1.36, 4.96), P = 0.004; n = 218, see Additional File 4).