A new lymph node ratio-based staging system for rectosigmoid cancer: a retrospective study with external validation.

Area of Science:

• Oncology
• Surgical Oncology
• Cancer Staging

Background:

• Rectosigmoid cancer (RSC) staging is crucial for prognosis and treatment planning.
• The current American Joint Committee on Cancer (AJCC) tumor node metastasis (TNM) staging system may require refinement for optimal accuracy.
• Lymph node ratio (LNR) is an emerging metric in cancer prognostication.

Purpose of the Study:

• To evaluate the clinical utility of a novel AJCC TNM staging prediction model based on LNR in rectosigmoid cancer.
• To compare the prognostic predictive ability of the new LNR-based staging system against the established AJCC TNM system.
• To assess the impact of the new staging system on treatment decisions, specifically adjuvant chemotherapy.

Main Methods:

• Analysis of 1444 patients with nonmetastatic RSC from the National Cancer Institute Surveillance, Epidemiology, and Results database (2010-2016).
• Redefinition of AJCC N-stage using LNR cutoff points to create the T lymph node ratio M (TLNRM) staging system.
• Comparison of prognostic prediction accuracy between TLNRM and the traditional AJCC TNM staging system.
• External validation using data from 739 patients from a single institution.

Main Results:

• The TLNRM staging system, dividing patients into five N-stage groups (LNR0-5), demonstrated significantly different 5-year overall survival (OS) rates (P <0.05).
• Decision curve analysis indicated superior net income for the TLNRM system compared to the eighth edition AJCC TNM system.
• The TLNRM system showed higher sensitivity in prognosis prediction, evidenced by smaller Akaike and Bayesian information criteria.
• TLNRM stages II and III patients benefited from adjuvant chemotherapy, unlike TNM stage II patients, a finding confirmed by external validation.

Conclusions:

• The novel TLNRM staging system outperforms the eighth edition AJCC staging system in staging and prognosis prediction for rectosigmoid cancer.
• The TLNRM system demonstrates potential as an effective clinical tool for managing RSC.
• The findings support the use of LNR in refining cancer staging for improved patient outcomes.