Proposal of a novel stage grouping of the Eighth Edition of American Joint Committee on Cancer TNM Staging System for Gastric Cancer: results from a retrospective study of 30 years clinical data from a single institute in China

ABSTRACT

Objectives

To improve the prognostic accuracy of 8th edition of American Joint Committee on Cancer TNM staging system for gastric cancer by reclassifying N3a category.

Methods

1446 patients who underwent R0 surgery for histologically proven gastric cancers with ≥16 lymph nodes retrieved were selected.

Results

Significant prognostic difference was observed among patients in N3a category (‘7–10’ group vs ‘11–15’ group; P = 0.029). We proposed a revised pN category in which patients with ‘7–10’ metastatic lymph nodes were categorized as r-N3a, ‘11–15’ as r-N3b, and ‘>15’ as r-N3c. Prognosis for patients in T2r-N3aM0 was similar to that of patients in T4aN0M0/T3N1M0/T2N2M0/T1r-N3bM0 (P = 0.584), but significantly better than that of patients in T4bN0M0/T4aN1-2M0/T3N2M0/T2r-N3bM0 (P = 0.031). Similarly, prognoses for patients in T3r-N3aM0 and T4ar-N3aM0 were similar to that of patients in T4bN0M0/T4aN1-2M0/T3N2M0/T2r-N3bM0 (P = 0.136; P = 0.193), but significantly better than that of patients in T4bN1-2M0/T4ar-N3bM0/T3r-N3bM0/T1-2r-N3cM0 (P = 0.011; P = 0.017). A revised TNM system was also proposed, in which T2r-N3aM0 was incorporated into stage IIB, T3r-N3aM0 and T4ar-N3aM0 into stage IIIA. The revised TNM system had better homogeneity, discriminatory ability, and monotonicity of gradients than the 8th edition system.

Conclusion

Patients with 7–10 metastatic lymph nodes in T2-T4a categories should be considered lower stage in the final TNM stage.

KEYWORDS:

• Gastric cancer
• revised N3a category
• revised TNM category
• overestimate
• prognosis

Article highlights

• We question the rationality of the current pN category in prognostic assessment.

• We put forward a novel revised pN category in which patients with ‘7-10’ metastatic lymph nodes (LNs) were classified as r-N3a category, ‘11-15’ metastatic LNs as r-N3b category, and ‘>15’ metastatic LNs as ‘r-N3c’ category.

• The revised pN category we put forward is superior to the 8th edition pN category.

• We propose a revision of the 8th edition TNM system based on the revised pN category, in which T2r-N3aM0 was incorporated into stage IIB, T3r-N3aM0 and T4ar-N3aM0 into stage IIIA.

• The revised TNM system is an independent factor predicting patient survival while the 8th edition TNM system is replaced. What’s more, the revised TNM system has better homogeneity, discriminatory ability, and monotonicity of gradients than the 8th edition TNM system.

• Table 3 is the best summary of our research, which is also a better presentation to improve the staging of 8th edition TNM classification on gastric cancer.

Acknowledgments

First and foremost, I would like to show my deepest gratitude to my supervisors, Dr Huimian Xu and Dr Baojun Huang. I cannot finish my manuscript without their enlightening guidance and impressive patience. Their rigorous and modest academic attitude encourages me. I would not withhold my sincere appreciation to all the teachers and classmates in the Department of Surgical Oncology of the First Affiliated Hospital of China Medical University, without their encouragement and support this manuscript cannot be completed.

Declaration of interest

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

Reviewer disclosures

Peer reviewers on this manuscript have no relevant financial or other relationships to disclose.

Geolocation Information

This study was carried out in Shenyang City, Shenyang City, Liaoning Province, People’s Republic of China.

Additional information

Funding

This paper was supported by the National Natural Science Foundation of China, grant number: NO. 81272716; and the Shenyang Municipal Science and Technology Plan, Project number: 17-231-1-49.