Lymph node yield as a surrogate marker for tumour biology and prognosis in colon cancer

Abstract Background We interrogated two large national databases to explore the underlying mechanisms and institutional effects of the known association of enhanced survival with a higher lymph node yield (LNY) in non-metastatic colon cancer. Method Clinical and pathological data for stage I-III colon adenocarcinomas were extracted from the CORECT-R (England, 2010–2020) and SEER database (USA, 2000–2020). A lymph node (LN) cut-off for the lack of clinically significant increase in nodal positivity was identified. A multivariable Cox-regression model was developed to study the effect of LNY on overall survival. Furthermore, institutional variations in LNY and their impact on survival were explored. Results Patients were retrospectively included from the CORECT-R (n = 84,116) and SEER (n = 287,974) databases. No significant increase in nodal positivity was noted after a LN cut-off of 9. However, improved survival was noted in node-negative and node-positive cancers beyond this cut-off. A 1% risk-reduction concerning overall survival was reported for every node counted. We identified ten outlying institutions across England with an observed LNY greater or less than the expected, with no impact on overall survival. Discussions We advocate incorporating LNY into patient and clinician discussions as a surrogate marker of tumour biology and prognosis rather than using LNY as a quality indicator.