Prognostic implication of metastatic lymph node ratio in node-positive rectal cancer

Area of Science:

• Oncology
• Surgical Pathology
• Cancer Prognostics

Background:

• Stage III rectal cancer presents a significant clinical challenge.
• Accurate prognostic stratification of lymph node (LN) involvement is crucial for treatment planning.

Purpose of the Study:

• To determine the prognostic significance of the lymph node ratio (LNR) in patients with stage III rectal cancer.
• To evaluate the LNR as a tool for stratifying patients based on LN metastasis.

Main Methods:

• Retrospective review of 175 patients with stage III rectal cancer undergoing R0 resection.
• Stratification of LN disease using the American Joint Committee on Cancer/International Union Against Cancer nodal classification (pN) and LNR quartiles.
• Survival analysis using Kaplan-Meier curves, log rank test, and Cox proportional hazards model.

Main Results:

• A strong correlation was observed between the number of metastatic LNs and the LNR (r = 0.8681, P < 0.0001).
• Five-year disease-free survival (DFS) significantly differed across LNR quartiles (89.6% for LNR1, 55.8% for LNR2, 18.2% for LNR3; P < 0.0001).
• The LNR was identified as a significant independent prognostic factor; LNR2 and LNR3 were associated with substantially increased risk compared to LNR1.

Conclusions:

• Ratio-based lymph node staging, incorporating the number of examined LNs, offers a simple and reliable prognostic system for stage III rectal cancer.
• The LNR provides valuable information beyond traditional nodal classification, reflecting the quality of lymph node dissection.
• This approach aids in more precise prognostic stratification and potentially personalized treatment strategies.