Statistical analysis
The associations of prognostic factors with death were assessed using
the chi-squared test for univariate analysis and analyzed with Cox
proportional hazards regression for multivariate analysis (considering
the time from chemotherapy initiation to the last follow-up time or
death) to establish the hazard ratio (HR) of death in 298 GTN patients.
Only positive variables in univariate analysis were enter into the
multifactor model, except for FIGO stage and FIGO score. Descriptive
analyses were performed for clinical characteristics, treatment, and
prognosis information of 11 ultra-high-risk GTN patients with liver or
brain metastases. The rates of CR after initial treatment and resistance
to initial treatment in ultra-high-risk GTN patients were compared
between those with and without liver or brain metastases using the
chi-squared test. Survival time was compared in 298 GTN patients
stratified according to liver or brain metastases using the log-rank
test. Survival time was compared in 18 high-risk GTN patients stratified
according to having/not having liver or brain metastases was compared by
the log-rank test. A secondary analysis of longer-term survival was
performed at six years (72 months), which was the median follow-up time
for the entire cohort. There were no missing values. P -values
<0.05 were considered to be statistically significant. All
statistical analyses were conducted using SAS version 9.4 (SAS
Institute, Inc., Cary, NC, USA).