The incidence of EGC was 11.96% in our 1004 patients, which is similar to that in another study in China [18]. In the western hemisphere, EGC accounts for 4–16% of all gastric carcinoma cases [19]. In South Korea, the proportion of EGC accounts for 47.4% of all diagnosed GCs in 2004 [20], while in Japan, the proportion of EGC accounts for approximately 30–50% of all GCs [21]. The differences in incidence may be related to screening strategies and various economic and health levels in different countries.
In our study, the LNM rate in EGC was 15.8%. Shen L et al [18] reported that LNM was observed in 12.20% of EGC patients. In another study [22], LNM was reported in 19.7% of EGC cases. The reported rates range from 5.7–20% of patients [23–28]. In our study, the node-positive rate of patients with EGC was 17.8% in those with tumours in the mucosal layer and 15.2% in those with tumours in the submucosal layer. As previously reported [28–29], once the tumour has invaded the submucosal layer, the rate of LNM increases significantly. However, we did not obtain the same result.
According to previous reports, anaemia is closely correlated with worse outcomes in cancer patients. For example, some studies have shown that anaemic patients with laryngeal [30], cervical [31], ovarian [32] and lung cancers exhibit worse survival [33,34]. A Korean study has shown that pretreatment anaemia is associated with poorer survival in patients with stage I and II GC [35]. Xuechao Liu et al found that preoperative anaemia, even mild anaemia, was an important predictor of postoperative survival of patients with TNM III GC [36]. Our study showed that the preoperative Hb level was an independent prognostic factor in EGC. This is a unique finding compared with the findings in previous reports. The Hb level may affect the prognosis of early-stage GC. These results may provide information used in the treatment of EGC. In the future, we will study the exact mechanism by which the preoperative Hb level influences EGC.
Many studies have evaluated LNM in EGC and have confirmed that LNM is the most crucial prognostic factor for EGC [37–40]. We also obtained this result. LNM and preoperative Hb level were independent prognostic factors in EGC. Fig. 1 shows that the prognosis of EGC patients with different N stages was significantly different (p = 0.000). Patients who were lymph node-positive were younger and had higher Ca–199 values than those who were lymph node-negative. A multivariate logistic analysis for variables associated with LNM in EGC showed that age, Ca–199 and macroscopic tumour type were independent prognostic factors. In a study of 376 patients with EGC who underwent gastrectomy, Lim et al [41] found that macroscopic tumour type was related to LNM. Another publication [18] also revealed that macroscopic tumour type and other factors were independent risk factors for LNM. These studies suggest that macroscopic tumour type is important for predicting LNM in EGC. Moreover, Roviello et al [42] analysed 652 EGC patients with LNM and confirmed age (p = 0.012, RS = 0.97) as an independent predictor of nodal involvement. Fukuhara [43] also showed that younger age (OR, 1.11; 95% CI, 1.01–1.12; p = 0.046) was a significant predictor of LNM. Thus, younger patients with EGC may have more LNMs than older patients.
Limitations of this study include an inability to obtain a specific cut-off value for the preoperative Hb for predictive prognosis. We anticipate larger databases for further validation in the future. Another limitation was that this study analysed data originating from a single centre. In the future, we expect to perform a multi-centre and large-scale collaborative study to further demonstrate the prognostic significance of the preoperative Hb level in EGC.
In conclusion, we found that the preoperative Hb level and LNM were independent prognostic factors in EGC. Age, Ca–199 level and macroscopic tumour type were independent prognostic factors of LNM in EGC. The preoperative Hb level and LNM may help surgeons make better treatment decisions in the perioperative period.