Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
p value is calculated by chi‐square test or Fisher's exact test.
Abbreviations: CI, confidence interval; ER, estrogen receptor; HER2, human epidermal growth receptor 2; HR, hazard ratio; PR, progesterone receptor.
