Abstract and Introduction
Abstract
Objectives: The TNM classification is the main tool for lymph node (LN) staging in gastric cancer (GC). However, alternative LN staging systems have been proposed, and the role of features other than the number of metastatic LNs is being investigated. Our aim is to discuss the main challenges of LN assessment in GC.
Methods: Comprehensive review of the literature on alternative LN staging systems, examined LNs, sentinel LN (SLN) biopsy, LN micrometastases (LNMIs), extracapsular extension (ECE), and tumor deposits (TDs) in GC.
Results: Many controversies exist regarding LN assessment in GC. The TNM classification shows excellent prognostic performance, but alternative prognostic methods such as the LN ratio or log odds of positive LNs have demonstrated to be better than the TNM system in terms of prognostic accuracy. The value of SLN biopsy and LNMIs in GC is still unclear, and several challenges concerning their clinical impact and pathologic analysis must be overcome before their introduction in clinical practice. Most authors have identified ECE and TDs as independent prognostic factors for survival in GC.
Conclusions: Further studies should be performed to evaluate the impact of these features on the TNM classification and patient outcomes, as well as to standardize alternative LN staging systems.
Introduction
Gastric cancer (GC) is the fifth most common malignancy and the third cause of cancer-related mortality worldwide. Its incidence varies between geographical regions: it is more frequent in Eastern Asia and in some countries of Eastern Europe and South America.[1] In Western countries, GC is usually detected at advanced stages, and the 5-year survival rate is estimated to be as low as 30%.[2] In Eastern countries, patients are diagnosed at earlier stages and show better prognosis due to the implementation of screening programs.[3] The main prognostic tool for GC stratification is the TNM system, published by the American Joint Committee on Cancer (AJCC). This classification includes tumor depth (T stage), lymph node metastases (N stage), and distant metastases (M stage). Lymph node (LN) involvement is considered one of the most important prognosticators in resected GC.[4] The last TNM classification for LN staging is based on the number of metastatic LNs, and it has shown to be useful for predicting patient prognosis and guiding treatment. However, its limitations are being underscored, and several alternative LN staging systems have been proposed, such as LN ratio, log odds of positive LNs, or revised anatomic-based classifications.[4,5] In addition, the role of the number of harvested LNs, sentinel LN navigation surgery, micrometastases, extracapsular extension, or tumor deposits is being investigated. In this review, we have summarized the main advances and controversies in the LN staging of GC. Our aim is to provide an overview on the surgical, pathologic, and clinical issues currently being discussed in the literature.