Lymph node identification following neoadjuvant therapy in rectal cancer: A stage-stratified analysis using the
Brett L Ecker1, Emily C Paulson1,2, Jashodeep Datta1
1Department of Surgery, University of Pennsylvania, Philadelphia, Pennsylvania.
Background And Objectives:
Neoadjuvant chemoradiation (nCRT) for rectal adenocarcinoma reduces lymph node (LN) identification following surgical resection. We sought to evaluate the relationship between LN identification following nCRT and disease-specific survival (DSS), stratified by pathologic stage.
Methods:
The SEER-Medicare database (2000-2009) was queried for 1,216 pathologic stage I-III rectal cancer patients who underwent nCRT followed by curative-intent resection. Cox regressions evaluated the association between pathologic stage and DSS for LN cut-points from ≥2 up to ≥12 LNs.
Results:
Extent of LN identification did not influence DSS in ypStage I or ypStage III disease; in particular, the 12 LN cut-point was not associated with DSS for ypStage I (HR 1.29, P = 0.51) or ypStage III (HR 1.08, P = 0.42) patients. In ypStage II patients, actuarial survival improved continually with increasing lymph node identification up to ≥12 LNs. The 5 LN cut-point was associated with the greatest reduction of risk of cancer death (HR 0.56, P = 0.006), with decreasing magnitudes of survival benefit associated with nodal counts beyond 5 LN. The 12 LN cut-point was not associated with DSS in ypStage II patients (HR 0.67, P = 0.07).
Conclusion:
The association between DSS and LN identification is a dynamic outcome that varies by pathologic stage, with unique prognostic significance for ypStage II patients.
