ESR1 and breast cancer: Whereas there was no statistically significant difference in BC (mean difference: −0.18, 95% CI: −0.89 to 0.52, p = 0.602), PTK7 expression in LN metastasis was strongly linked to ER- status (mean difference: 1.26, 95% CI: 0.46 to 2.06, p = 0.003), PR- status (mean difference: 0.87, 95% CI: 0.09 to 1.66, p = 0.030) and HER2-status (mean difference: -1.5, 95% CI: −2.39 to −0.65, p = 0.001).