Kaplan-Meier curves with univariate analyses (log-rank) for patients with low SPHK1 expression versus high SPHK1 expression tumors. (A) Patients with low SPHK1 expression (bold line) had a cumulative 5-year survival rate of 93.4% (95% confidence interval, 0.854-0.914), compared to the 46.3% for patients with high SPHK1 expression (dotted line; 95% confidence interval, 0.369-0.573). (B) Statistical analysis of the difference between the tumors with high and low SPHK1 expression in the clinical stages I and II (left) and clinical stages III and IV (right) patient subgroups. (C) Statistical analysis of the difference between tumors with high and low SPHK1 expression in the poor pathologic differentiation (left) and well pathologic differentiation (right) patient subgroups. P values were calculated using the log-rank test.