| Aim ELNs(Examined Lymph Node counts)is an important factor that can significantly affect lymph node staging and prognosis assessment after curative gastric resection.This propensity score matching analysis assessed the influence of ELNs on stage migration and survival in node-negative(pN0)gastric cancer(GC)patients.Methods We performed a retrospective analysis of 7,620 GC patients who underwent curative gastric resection in three Chinese medical centers.Propensity score matching(PSM)was used to reduce the confounding effects between the pN0 GC patients with ELNs <16 or ≥16.The relationship between ELNs and Overall Survival(OS)of pN0 gastric cancer patients was evaluated by survival analysis and Multiple Cox analysis.Survival differences among various subgroups of pN0 GC patients were analyzed to assess the impact of the ELNs on the stage migration in accordance with the OS of pN0 GC patientsResults 1.A total of 7620 patients with gastric cancer were included in this study,including 5378 males(70.6%)and 2242 females(29.4%).2797 patients(36.7%)had no lymph node metastasis,and 4823 patients(63.3%)had lymph node metastasis.The average number of examined lymph nodes was 23.2 ± 13.1(median 21.0,range 1-118);2.Patients with ELNs <16 were matched to patients with ELN ≥16 based on similar estimated propensity scores to balance the covariates in the two groups and reduce selection bias.Before PSM,there were 2292 patients(30.0%)with ELNs <16 and 5328(70.0%)patients had ELN ≥16.After PSM,there were 1,843 patients in each group and there was no significant statistical difference in each variable between the two groups.3.PN0 GC patients with ELNs <16 were matched to pN0 GC patients with ELN ≥16 based on similar estimated propensity scores.Before PSM,there were 1,031 pN0 GC patients with ELNs <16 and 1,762 pN0 GC patients with ELNs ≥16.After PSM,there were 825 patients with ELNs <16 and 826 patients with ELNs ≥16 and the backgrounds two groups were well-balanced.4.We further analyzed the matched pN0 GC patients.Survival analyses revealed that the ELNs count was positively correlated with the OS(P = 0.001).Multiple Cox analysis indicated that the ELNs count was an independent predictor of the OS in pN0 GC patients.5.Stage migration was detected between the following subgroups of pN0 GC patients 1)p T2N0M0(IB,ELNs <16)vs.p T3N0M0(IIA,ELNs≥16)(P = 0.371);2)p T2N0M0(IB,ELNs < 16)vs.p T4 a N0M0(IIB,ELNs ≥16)(P = 0.100);3)p T3N0M0(IIA,ELNs <16)vs.p T4 a N0M0(IIB,ELNs ≥16)(P = 0.859);4)p T3N0M0(IIA,ELNs <16)vs.p T4 b N0M0(IIIA,ELNs≥16)(P = 0.397);5)p T4 a N0M0(IIB,ELNs <16)vs.p T4 b N0M0(IIIA,ELNs≥16)(P = 0.831).We hypothesized an increasing number of ELNs may transform a specific p TNM stage into a higher stage.Then we used the matched all-stage GC patients to test this hypothesis.The hypotheses were disproven in: 1)stage p T2N0M0(IB,ELNs <16)vs.p T2N2M0(IIB,ELNs ≥16)(P =0.004)and 2)stage p T3N0M0(IIA,ELNs <16)vs.p T3N2M0(IIIA,ELNs ≥16)(P <0.001).The hypotheses were proven in: 1)stage p T3N0M0(IIA,ELNs <16)vs.p T3N1M0(IIB,ELNs ≥16)(P = 0.079)and 2)stage p T4 a N0M0(IIB,ELNs <16)vs.p T4 a N1M0(IIIA,ELNs ≥16)(P = 0.921)Conclusions 1.ELNs correlated with the prognosis of pN0 GC patients.The prognosis of ELNs ≥16 group was significantly better than that of ELNs <16 group(P = 0.001).And ELNs were independent prognostic factors for patients with pN0 gastric cancer(HR: 0.644,95% CI: 0.516-0.804,P <0.001).2.We show that stage migration can be detected in pN0 GC patients.In this study,stage migration mainly occurred between stage p T2N0M0 and p T2N1M0,stage p T3N0M0 and p T3N1M0,stage p T4 a N0M0 and p T4 a N1M0.Increasing the ELNs can gradually reduce or prevent stage migration. |
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