Prognostic Impact of the Number of Retrieved Lymph Nodes in Patients with Gastric Cancer

Background: In gastric cancer, although at least 16 lymph nodes of retrieved lymph nodes (RLNs) are recommended for nodal staging in Japanese Classification of Gastric Carcinoma and TNM classifications, we wished to clarify their appropriateness.

Study Design: A total of 1289 consecutive gastric cancer patients, who underwent gastrectomy between 1997 and 2011, were analyzed retrospectively.

Results: (i) The patients were divided into two groups using a cut-off RLN number of 16 (RLN < 16 or RLN ≥ 16). There were significant differences in the survival rates of patients in pStage II (P < 0.0001) and III (P = 0.0009), but not those of patients in pStage I (P = 0.0627) and IV (P = 0.1553). (ii) In 498 consecutive patients in pStage II and III, compared with patients in the RLN ≥ 16 group, those in the RLN < 16 group had a significantly higher incidence of older age (P = 0.0004) and positive lymph node ratio (PLNR) (P < 0.0001). Univariate and multivariate analyses showed that an RLN number of less than 16 was an independent poor prognostic factor (P < 0.0001, HR 2.48 [95% CI: 1.60-3.70]). (iii) A cut-off RLN number of 16 could cause the stage migration effect in pStage II or III patients. A cut-off RLN number of 25 or more could eliminate the prognostic effect.

Conclusion: The RLN number may potentially affect the prognosis and the stage migration in pStage II or III gastric cancer patients. An RLN number of 25 or more could be sufficient for nodal staging.