STATISTICAL METHODS:
The descriptive analysis included the absolute and relative frequency
for categorical variables. Comparison between groups was carried out
using the Chi-square test or Fisher’s exact test. Variables for the
survival analysis were age, primary site, metastatic site, baseline LDH,
chemotherapy regimen, response to chemotherapy and surgery. The survival
curve was estimated for each variable using the Kaplan-Meier method. The
comparison between curves was obtained by the log-rank test. The Cox
regression model was used to assess the effect of the variables on
survival (multivariate analysis to calculate hazard ratios), which
included variables with the following characteristics according to the
Kaplan-Meier analysis with a significant difference (p<0.05).
The level of significance established for all analyses was 5%. All
analyses were performed using the software SPSS®20.0 for Windows
(Statistical Package for Social Sciences, IBM, USA).