Importance of the pattern of lymph node metastasis in upper and lower gastric cancer

Abstract

The article by Yuan et al accessed the clinicopathologic and prognostic significance of the patterns of lymph node (LN) metastasis in upper and lower gastric cancer (GC). In this article, we will analyze both the strengths and limitations of this paper. The study’s methodology seems appropriate and proper statistical analyses were applied to identify significant variables. The authors applied the Cox regression model to identify independent risk factors and Kaplan-Meier survival curves to assess prognosis. The researchers found notable differences in clinicopathologic variables between patients with upper and lower GC. Additionally, they identified specific LN stations more prone to metastasis in different Siewert classifications of GC. Despite the study’s detailed analysis, it would have been beneficial to explore whether there were survival differences among upper GC patients based on the Siewert classification. Furthermore, the study should have addressed potential confounding factors that might have influenced the results. A more comprehensive analysis could have been achieved by comparing survival outcomes based on LN metastasis patterns. Overall, this article is relevant and provides valuable insights into the significance of LN metastasis patterns in upper GC patients.

Key Words: Gastric cancer; Lymph node metastasis; Risk factor; Survival; Lymph node

Core Tip: Upper gastric cancer (GC) has a significantly greater degree of malignancy than lower GC. In upper GC, the rate of lymph node (LN) metastasis was greater in groups number 1, 2, 3, and 7 among the different subtypes. In lower GC, the rate of LN metastasis was greater in groups number 3-8. Pathological type, histological grade, tumor stage, tumor-node-metastasis stage, and vascular invasion independently influenced the occurrence of LN metastasis. Age, pathological type, tumor stage, nodes stage, tumor-node-metastasis stage, vascular invasion, and absence of adjuvant chemotherapy independently influenced the prognosis.

TO THE EDITOR

We are pleased to read the interesting article by Yuan et al[1], which accessed the clinicopathologic and prognostic significance of the patterns of lymph node (LN) metastasis in upper and lower gastric cancer (GC). The authors applied the Cox regression model to identify independent risk factors and Kaplan-Meier survival curves to assess prognosis. They identified certain clinicopathologic variables significantly different in upper and lower GC patients and also identified the LN station prone to metastasis in different Siewert classifications of GC. Pathological type, histological grade, pT (tumor) stage, tumor-node-metastasis (pTNM) stage, and vascular invasion were associated with LN metastasis. Similarly, age, pathological type, pT stage, nodes stage, pTNM stage, vascular invasion, and absence of adjuvant chemotherapy independently influenced the prognosis of GC patients. Herein, we will analyze the clinical significance of metastatic LN distribution in GC patients.

Patterns of LN metastasis in GC

LN metastasis is a key prognostic indicator in many different types of cancer, including GC. The clinical significance of LN metastasis is crucial in GC as it is a predictor of poor prognosis, and adequate sampling is required for staging, prognostic prediction, and the selection of effective treatment strategies[2,3]. There are well-known LN staging systems for GC including the TNM system purposed by the International Union for Cancer Control/American Joint Committee on Cancer and the Japanese Gastric Cancer Association staging system[4-6]. The pattern of LN metastases in GC depends on the primary tumor location and its characteristics. The individualized treatment approach has been developed based on tumor location to determine the extent of lymphadenectomy[7]. The Siewert classification is used for the assessment of LN spread and is the most commonly used classification for cancers of the esophagogastric junction[8]. Different types of upper GC cancer have different incidences of mediastinal and abdominal LN metastases, and different surgical approaches have been proposed for radical treatment strategies. Most of the published studies have reported that the Siwert type II GC are prone to metastasis in upper perigastric nodes (LN 1, 2, and 3), whereas, the incidence of LN metastases in Siwert type III GC has a higher risk of metastases in 4sa, 4sb, 4d, 8a, 9, and 11p LNs[2,8]. It is important to note that both Siwert type II and III have a certain risk of metastases to the mediastinal nodes, celiac artery, and splenic artery. Finally, in lower GC, the risk of LN metastasis was higher in group number 3-8. As research continues to identify novel LN classification systems, analyzing the prognostic value of tumor location and its correlation with metastatic LN stations may provide new insights that could improve GC management[5].

Key aspects of metastatic LN distribution in GC

The International Union for Cancer Control/American Joint Committee on Cancer guidelines and the current Japanese Gastric Cancer Association staging system are based on the LN classification based on the number of metastatic LNs. The numerical classification system has multiple advantages as it is simple, easily reproducible, and has better prognostic ability[6]. In the present study, the authors have identified certain LN stations that were prone to metastasis based on the tumor location. Moreover, they have also identified that signet-ring cell pathology; moderately differentiated, poorly differentiated, or undifferentiated tumor status; higher pT stage; higher pTNM stage, and vascular invasion were independent risk factors for LN metastasis. This study has highlighted the clinical significance of metastatic LN distribution patterns, as the clinicians can diligently evaluate the risk of LN stations prone to metastasis based on the anatomical location of the tumor, and therefore plan for surgical resection and pathologic assessment of high-risk LNs.

In summary, despite the detailed analysis, we would love to see if there was any survival difference between the upper GC patients based on the Siewert classification of upper GC. At the same time, authors should be concerned if the sample size is large enough for statistically meaningful subgroup analyses. More detailed information could have been obtained by comparing the survival based on the pattern of LN metastasis. Furthermore, the authors have used Kaplan-Meier analysis and Cox regression models for survival analysis, but the potential confounders distorting the outcomes were not described. Overall, the article is relevant and has tried to explore the significance of the LN metastasis pattern in upper GC patients. Future studies should consider multivariate-adjusted survival analysis and external validation in independent/multicenter cohorts to support the identified results.

Conclusions

In conclusion, identifying high-risk LN stations based on tumor location in GC can enhance preoperative assessment, guide lymphadenectomy decisions, improve LN retrieval, and refine prognosis predictions based on metastatic LN stations. Future studies should incorporate multivariate-adjusted survival analyses and validate findings in independent multicenter cohorts to strengthen these conclusions.

ACKNOWLEDGEMENTS

We would like to thank all the reviewers and editors who were involved in improving the quality of our manuscript.