Prognostic value of metastatic lymph node ratio as an additional tool to the TNM stage system in gastric cancer
Introduction
Gastric cancer is a common solid malignancy in the world, with especially high incidence in the Eastern Asia. It is estimated that 952,000 new cases of gastric cancer, representing 6.8% of the total cancer were diagnosed in the world in 2012, making it the fifth most common malignancy and the third leading cause of death due to cancer.1, 2 The goal of staging for gastric cancer is to predict the prognosis of the patients. The depth of tumor invasion (T) and nodal involvement (N) are currently the most important prognostic factors in surgically treatable gastric cancer.3, 4, 5 A good staging system was defined as reflecting “decreased patient survival with increasing stage group, difference in survival between groups, and similar survival with in a group”.6 Nowadays, the most commonly used staging system for gastric cancer is the TNM system established collaboratively by American Joint Committee on Cancer (AJCC) and the International Union for Cancer Control (UICC). This TNM system stratifies patients on the basis of depth of primary invasion (T), number of metastatic positive lymph nodes (N), and presence of distant metastasis (M).7, 8 The 7th edition AJCC TNM stage system requires a minimum of 15 lymph nodes to be examined to determine the N stage. Specifically N1 refers to cases with 1–2 metastatic nodes. N2 refers to cases with 3–6 nodes and N3 with more than 6 nodes (N3a with 7–15 nodes, N3b with ≥16 nodes).8
In addition to the TNM staging system, alternative N staging system exists and one of the most promising one is the metastatic lymph node ratio (rN) which is defined as the ratio between the positive lymph nodes and the number of lymph nodes examined. Recently, several studies have evaluated the prognostic value of rN stage in gastric cancer and most of the studies concluded that the rN stage had better prognostic value than the traditional N stage in the TNM system.9, 10, 11, 12, 13, 14, 15 But the majority of these studies only evaluate the rN stage in patients with less than 15 lymph nodes examined. While rN stage proved to be useful for patients with insufficient lymph node examined, the prognostic value of rN in patients with >15 lymph nodes tested has not been compared with TNM system.9, 11, 13, 15
In this study, we investigated the prognostic value of the rN stage in patients with >15 lymph nodes examined and evaluated the rN stage as an independent prognostic factor for gastric cancer patients with curative resection and the possibility of rN stage as an additional tool to the 7th edition TNM stage system.
Section snippets
Study design and patients
All patients with gastric cancer surgically treated at Peking University Cancer Hospital from November 1995 to March 2007 were enrolled in this retrospective study. The inclusion criteria include: (1) pathologically-proved adenocarcinoma; (2) tumors arising in the distal stomach or arising in the proximal 5 cm but not crossing the esophagogastric junction as required by the 7th edition of the AJCC cancer staging manual16; (3) patients received radical gastrectomy with at least 15 lymph nodes
Patients characteristics
The demographic features and the tumor characteristics of the 745 patients included in this study are listed in Table 1. Among all the tumors, 44.4% were located in the lower third of the stomach and 19.7% were in the upper third. Early gastric cancer accounts for <10% and locally advanced gastric cancer accounts for 79.0%. A total of 42.7% (n = 318) patients received postoperative chemotherapy. The median number of lymph nodes examined is 22 (range 15–71) and the average metastasis positive
Discussion
Gastric cancer is one of the most common malignant tumor in the world. How to predict the prognosis after surgery is one of the most important questions to be answered. The TNM staging system is currently the most widely used nomograph to predict the survival of gastric cancer patients. The metastatic lymph node status is one of the major parameters.
The N stage in the TNM staging system is based on the number of metastatic lymph nodes and is a powerful prognostic factor. A minimum number of 15
Conflict of interest
No commercial conflicts of interest is involved in the subject of study.
Disclosure
Xiao-Jiang Wu and other co-authors have no commercial conflicts of interest in the subject of study.
Acknowledgment
Supported by Open Fund of Key Laboratory of Carcinogenesis, 2015 Ministry of Education (1122-02-1402).
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Topographic lymph node staging system shows prognostic superiority compared to the 8th edition of AJCC TNM in gastric cancer. A western monocentric experience
2020, Surgical OncologyCitation Excerpt :The minimum number required for accurate staging has not been standardized so far. This can cause understaging of disease and lead to improper oncologic treatment [26–28]. Kong et al. [29] suggested that because the proportion of advanced pN stage increases with the number of examined LNs, the minimum number of 16 LNs required for “accurate staging” is not sufficient.
The 8th edition American Joint Committee on gastric cancer pathological staging classification performs well in a population with high proportion of locally advanced disease
2018, European Journal of Surgical OncologyCitation Excerpt :Lymph node ratio was originally developed to overcome the inadequate lymph node retrieval and avoid incorrect tumor staging that would lead to stage migration [21]. Several studies have demonstrated that LNR better stratified patient survival than the AJCC nodal status [22–24]. In the CGMH/TVGH cohort, 604 (11%) patients were categorized as N3b disease and 96.7% of them were allocated to stage IIIC by the AJCC8.
Impact of lymph node ratio in selecting patients with resected gastric cancer for adjuvant therapy
2017, Surgery (United States)Citation Excerpt :These data suggested strongly that further risk prediction was need to refine better which patients might benefit from adjuvant therapy. Rather than stratifying patients as simply N0 versus N1 when assessing extent of nodal disease, the ratio between metastatic and examined lymph nodes (LNR) has been proposed as a better predictor of long-term outcomes after resection of gastric cancer.20-26,28,39 The present study confirmed that LNR was a strong, independent prognostic indicator of tumor prognosis relative to other risk factors.
Evaluation of prognostic value and stage migration effect using positive lymph node ratio in gastric cancer
2017, European Journal of Surgical OncologyCitation Excerpt :The PLNR may thus contribute to stratification of prognosis and evaluation of stage migration effect in a single institute of Eastern country and may be a better common nodal staging system between Eastern and Western countries. Indeed, various cut-off values for the new staging system using the PLNR have been already suggested: 0.1, 0.225; 0.1, 0.2526; 0.1, 0.417; 0.2, 0.513–16; 0.2, 0.627; 0.3, 0.628; and 0.4, 0.8.29 Nevertheless, many issues must be addressed before the PLNR can be translated into a clinically useful nodal staging system in gastric cancer patients.30
Nomogram for 5-year relapse-free survival of a patient with advanced gastric cancer after surgery
2016, International Journal of SurgeryCitation Excerpt :However, different prognoses were frequently observed among patients at the same stage. These differences may be due to other prognostic factors such as age, sex, tumor size, or histological type [3–6]. In particular, outcomes of patients who have undergone curative surgery for advanced gastric cancer and been diagnosed with pathological stage II or III disease are heterogeneous.
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These authors are contributed equally to this study.