Data are expressed as mean SEM, or as median and
range. The t test was used to calculate differences between
continuous variables. Survival and recurrence-free survival
were calculated with the use of the Kaplan-Meier method, and
survival curves were compared using the log-rank test. The
threshold of significance was set at P .05. The Graphpad
software package (Graphpad Software Inc, San Diego, CA) was
used for all statistical analyses.