Fig. 5

Kaplan – Meier survival curves of overall survival according to the pathological tumor stage and lymph node metastasis

A: The correlation between the different pathological tumor stages and overall survival (OS). Tumor stages were divided into two groups, one composed of early stages I and II and another group comprised of late tumor stages III and IV; B: The correlation between lymph node metastasis status and overall survival (OS). OS was defined as the duration from the time of surgery to the time of death or the last follow-up appointment. P-values of ≤ 0.05 were regarded as statistically significant