Optimizing nodal and staging classification in low rectal cancers with lateral node metastasis: multicentre...

Area of Science:

• Oncology
• Surgical Oncology
• Rectal Cancer Research

Background:

• Lateral node metastasis in low rectal cancer is associated with poor prognosis.
• Existing nodal classification systems may not fully capture the prognostic impact of lateral node involvement.
• Variability in patient survival based on lateral metastatic status requires further investigation.

Purpose of the Study:

• To assess the prognostic value of lateral node involvement in stage III low rectal cancer.
• To develop and validate a modified nodal classification system for rectal cancer.
• To compare the efficacy of the new classification with existing TNM and Japanese systems.

Main Methods:

• Retrospective review of 1250 patients with stage III low rectal cancer who underwent lateral node dissection.
• Development of a new nodal system using a 1995-2006 cohort (n=742).
• Validation of the new system using a 2007-2013 cohort (n=508) and comparison with TNM and Japanese classifications using AIC and c-index.

Main Results:

• A modified N classification was created, upgrading TNM-N1 and N2a cancers with specific lateral node features to N2a and N2b, respectively.
• The modified classification demonstrated superior prognostic performance (AIC=2661.08, c-index=0.6477) compared to TNM (AIC=2662.36, c-index=0.6457) and Japanese systems (AIC=2684.06, c-index=0.6302).
• Findings were validated in the second patient cohort.

Conclusions:

• A modified nodal system accurately reflects the prognostic significance of lateral node metastasis in low rectal cancer.
• This new classification improves risk stratification and prediction of survival outcomes.
• The proposed system offers enhanced accuracy over current staging methods for rectal cancer.