Lymph Node Yield and Long-Term Mortality Risk in Patients with Colon Cancer: A 20-Year Follow-Up National Study.

BACKGROUND

Lymph node status is a well-established prognostic factor for colon cancer, but the optimal number of nodes for accurate staging remains unclear. This study explored the relationship between lymph node yield (LNY) and 5-year mortality rates in colon cancer patients in New Zealand.

METHODS

Data from the New Zealand Cancer Registry were retrospectively analyzed for patients with TNM stage I, II, and III colon cancer between August 2003 and December 2021, with follow-up until January 2024. The primary outcome was the 5-year all-cause mortality rate, with LNY, age, sex, ethnicity, tumor site, district health board (DHB), and the number of positive nodes as covariates. Statistical analyses included univariate analysis, Cox regression modeling, and chi-squared tests.

RESULTS

LNY was a significant predictor of 5-year mortality risk (hazard ratio 0.985, p < 0.0001), adjusted for age, sex, ethnicity, tumor site, and DHB. The strongest association between LNY and mortality rate was observed at 12 nodes. Further increases in LNY beyond 22 nodes did not lead to statistically significant differences in mortality rates. Lymph node ratio (LNR) was strongly associated with survival in stage III colon cancer, independent of LNY and the number of positive nodes.

CONCLUSIONS

Higher LNY is significantly associated with reduced 5-year mortality rates in stage I-III colon cancer up to the 22-node mark. The strong correlation between LNR and mortality highlights its potential value for improving treatment planning in future clinical practice.