**2.5 Statistical analysis**

For qRT-PCR on primary tissues, the two-tailed Wilcoxon signed rank test was used for matched cases while the two-tailed Mann-Whitney *U* test was used for non-matched variables. Either the two-tailed Mann-Whitney *U* test or Kruskal-Wallis test, as appropriate, was used to establish relationships between hormone levels, ER mRNA and clinico-pathological features. Correlation coefficient (r) was calculated using two-tail Spearman correlation. Statistical differences were calculated using SPSS Statistics® for Windows™ v21 software from IBM SPSS Statistics (Feltham, UK) and GraphPad Prism® v6 (La Jolla, CA, USA). A value of *p* ≤ 0.05 was considered as statistically significant.
