Is the AJCC TNM staging system still appropriate for gastric cancer patients survival after 5 years?

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Abstract

Purpose

The aim of this study was to evaluate the prognostic value of the eighth AJCC TNM staging classification for patients with gastric cancer who had already survived for 5 years.

Patients and methods

Patients who underwent radical gastrectomy at a large eastern center were considered. The prognostic value of staging systems were assessed and compared. Additional external validation was performed using a dataset from the Surveillance, Epidemiology, and End Result (SEER) database.

Results

The 5-year overall survival (OS) rate for patients in the training set was 59.4%. With the prolongation of the survival time after surgery, the 5-year OS improved significantly (P < 0.05). However, there were no significant differences in survival curves among patients who have survived 5 years after surgery. The AUC and χ2 of the eighth AJCC classification for predicting of 5-year OS decreased gradually after surgery and appeared stable after 5 years. For patients who survived 5 years after surgery, we constructed a new TNM staging system (nTNM) according to the survival curves of T stage and N stage. A 2-step multivariate analysis showed that nTNM, age and sex were independent prognostic factors. The nTNM demonstrated superior prognostic stratification, with higher c-statistic and likelihood ratio chi-square scores and lower AIC values than those of the AJCC classification. Similar results were observed in the external validation set.

Conclusion

The nTNM predicted an additional survival more accurately than did the AJCC classification for patients who have survived 5 years after surgery; this may guide decisions regarding surveillance.

Introduction

Gastric cancer (GC) is the fifth most common malignancy and the third most common cause of cancer-related death worldwide [1]. In recent years, with the development of social economy and medical treatment, gastric cancer has been diagnosed earlier. In addition, the multimodal treatments for gastric cancer, especially new chemotherapeutic and biologic compounds, led to dramatically improve the patients’ survival. More gastric cancer patients obtain longer-term survival. Accurate staging is critical for predicting the prognosis of malignant tumors, clinical decision making and determining surveillance strategy. The American Joint Committee on Cancer (AJCC) tumor-lymph node-metastasis (TNM) classification is currently the most important prognostic indicator for gastric cancer [2]; it is based on pathological and survival data after surgery (gradually based on 5-year overall survival). However, the risk of death changes over time, and survival probability for patients who already have survived for several years may change with respect to the probability predicted immediately after surgery [3]. Whether the AJCC classification can still provide a valid assessment of long-term prognosis in patients who have survived a specified period of time after surgery has not yet been reported. Therefore, the purpose of this study was to evaluate the changes in long-term prognosis and the prognostic value of the AJCC staging system for GC patients with prolongation of survival time after surgery to provide a more accurate staging system for patients who survive a long time after surgery.

Section snippets

Study population

We retrospectively assessed all patients with resectable GC who were treated between January 1997 and December 2013 at Fujian Medical University Union Hospital (FMUUH). The inclusion criteria were defined as follows: (1) the presence of primary gastric cancer, (2) no distant metastasis, (3) R0 resection (no residual macroscopic or microscopic tumor), and (4) records of all relevant values. The following exclusion criteria were applied: (1) neoadjuvant chemotherapy, (2) histological

Clinicopathological characteristics

A total of 4556 patients were included in the development cohort (Supplemental Table 1). Of these patients, 3463 (76.0%) were male and 1093 (24.0%) were female. The mean patient age at the time of surgery was 59.5 years. Based on the primary site of gastric cancer, 1866 (41.0%), 745 (16.4%), 1317 (28.9%) and 628 (13.8%) had tumors located at lower-third (L), middle-third (M), upper-third (U) and two or more positions of the stomach, respectively. In terms of surgery, 2020 (44.3%) patients

Discussion

In recent years, the standard surgical approach and several adjuvant therapy patterns suggested for the treatment of gastric cancer led to improved survival rates; the 5-year survival rates for patients with gastric cancer has exceeded 50% [[9], [10], [11], [12]]. The AJCC TNM classification is important for assessing prognosis and determining appropriate treatment options for patients with gastric cancer; the 8th edition of the AJCC TNM classification system was published in 2016 [2]. For

Author contributions

Lin JX, Lin JP, Zheng CH, Huang CM and Li P conceived of the study, analyzed the data, and drafted the manuscript; Tu RH, Li P, Xie JW, Wang JB, and Li P helped revise the manuscript critically for important intellectual content; Lu J, Chen QY, Cao LL, and Lin M helped collect data and design the study.

Conflict of interest

There are no conflicts of interest or financial ties to disclose from any of author.

Human rights statement and informed consent

All procedures followed were in accordance with the ethical standards of the responsible committee on human experimentation (institutional and national) and with the Helsinki Declaration of 1964 and later versions. Informed consent or substitute for it was obtained from all patients for being included in the study.

Acknowledgements

A Scientific and technological innovation joint capital projects of Fujian Province, China (No.2016Y9031). Minimally invasive medical center of Fujian Province (No. [2017]171). The Science Foundation of the Fujian Province, China (Grant No. 2018J01307). Startup Fund for scientific research, Fujian Medical University (No. 2016QH024).

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    Lin JX and Lin JP contributed equally to this work and should be considered co-first authors.

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