For additional statistical analysis, we will estimate the
rate of CCA together with its 95 % confidence interval
(95%CI), particularly for early stage CCA, as well as the
corresponding rate for each relevant subgroup. Survival
analysis will be used to obtain survival profiles, including
time to detection, time to disease recurrence or death, survival
probability at 1–5 years, and hazard ratios with their
95%CIs. For these purposes, Kaplan-Meier methods and
cox regression will be used. All analyses will be performed
using Stata version 13 (StataCorp, College Station, TX).
Significance level is set as 0.05 and all statistical tests will
be two-sided.