Lymph node dissection for gastric cancer: a critical review

Prognostic Value of the Anatomic Region of Metastatic Lymph Nodes in the Current TNM Staging of Gastric Cancer

Purpose

The numeric N stage has replaced the topographic N stage in the current tumor node metastasis (TNM) staging in gastric carcinoma. However, the usefulness of the topographic N stage in the current TNM staging system is uncertain. We aimed to investigate the prognostic value of the topographic N stage in the current TNM staging system.

Materials and Methods

We reviewed the data of 3350 patients with gastric cancer who underwent curative gastrectomy. The anatomic regions of the metastatic lymph nodes (MLNs) were classified into 2 groups: perigastric and extra-perigastric. The prognostic value of the anatomic region was analyzed using a multivariate prognostic model with adjustments for the TNM stage.

Results

In patients with lymph node metastasis, extra-perigastric metastasis demonstrated significantly worse survival than perigastric metastasis alone (5-year survival rate, 39.6% vs. 73.1%, respectively, P<0.001). Extra-perigastric metastasis demonstrated significantly worse survival within the same pN stage; the multivariate analysis indicated that extra-perigastric metastasis was an independent poor prognostic factor (hazard ratio=1.33; 95% confidence interval=1.01–1.75). The anatomic region of the MLNs improved the goodness-of-fit (likelihood ratio statistics, 4.57; P=0.033) of the prognostic model using the TNM stage.

Conclusions

The anatomic region of MLNs has an independent prognostic value in the numeric N stage in the current TNM staging of gastric carcinoma.

Nodes staging score to quantify lymph nodes for examination in gastric cancer

The lymph nodal invasion diagnosis is critical for therapeutic-decision and follows up in gastric cancer. However, the number of nodes to be examined for nodal invasion diagnosis is still under controversy, and the model for quantifying risk of missing positive node is currently not reported yet. We analyzed the nodal invasion status of 13,857 gastric cancer samples with records of primary tumor stage, the number of examined and positive lymph nodes in the surveillance, epidemiology, and end results (SEER) database, fitting a beta-binomial model. The nodes need to be examined with different primary tumor stage were determined based on the model. Overall, examining 11 lymph nodes reduces the probability of missing positive nodes to <10%, and the currently median nodes dissected is adequate (12 nodes). While the number of nodes demands to be dissected for T1, T2, T3, and T4 subgroups are 6, 19, 40, and 66, respectively. The currently implemented median value for these samples was 12, 12, 13, and 16, separately. It implies that the number of nodes to be examined is sufficient for early gastric cancer (T1), but it is inadequate for middle and advanced gastric cancer (T2-T3). The clinical significance of nodal staging score was validated with survival information. In summary, we first quantified the lymph nodes to be examined during surgery using a beta-binomial model, and validated with survival information.

Perioperative chemotherapy in locally advanced gastric cancer

Gastric cancer is one of the most common cancers and a main cause of cancer-related death worldwide, since the majority of patients suffering of this malignancy are usually faced with a poor prognosis due to diagnosis at later stages. In order to improve treatment outcomes, the association of surgery with chemo and/or radiotherapy (multimodal therapy) has become the standard treatment for locally advanced stages. However, despite several treatment options currently available for management of these tumors, perioperative chemotherapy has been mainly accepted for the comprehensive therapeutic strategy including an appropriated D2-gastrectomy. This manuscript presents a (nonsystematic) critical review about the use of perioperative chemotherapy, with a special focus on the drugs delivery.

The role of perioperative radiotherapy in gastric cancer

Gastric cancer is one of the most common neoplasms and a main cause of cancer-related mortality worldwide. Surgery remains the mainstay for cure and is considered for all patients with potentially curable disease. However, despite the fact that surgery alone usually leads to favorable outcomes in early stage disease, late diagnosis usually means a poor prognosis. In these settings, multimodal therapy has become the established treatment for locally advanced tumors, while the high risk of locoregional relapse has favored the inclusion of radiotherapy in the comprehensive therapeutic strategy. We provide a critical, non-systematic review of gastric cancer and discuss the role of perioperative radiation therapy in its treatment.