Lymph Node Harvest and Survival Among Patients With Locally Advanced Appendiceal Adenocarcinoma.

[INTRODUCTION] Despite a distinct biology, the management of locally advanced appendiceal cancer, including recommended lymph node (LN) harvest and indications for adjuvant chemotherapy, is largely based on colon cancer treatment algorithms. We evaluated associations between LN harvest and survival in appendiceal cancer, and whether LN harvest informed which patients with node-negative disease benefited from adjuvant chemotherapy.

[METHODS] Patients with pathologic stage II-III appendiceal adenocarcinoma undergoing major resection (2004-2022) were identified from the National Cancer Database, and stratified by nodal status and harvest: pN0 with 0-11, 12-23, or ≥24 LNs, and pN1+. Multivariable Cox proportional hazards models were used to estimate overall survival and evaluate adjuvant chemotherapy benefit across LN harvest groups.

[RESULTS] Among 9743 patients, 15.4% were pN0 with 0-11 LNs, 36.1% with 12-23 LNs, 15.5% with ≥24 LNs, and 32.9% were pN1+. Those who were pN0 with 12-23 or ≥24 LNs harvested had lower risk of mortality than those with 0-11 LNs (adjusted hazard ratio [aHR] 0.73, 95% confidence interval [CI] 0.65-0.83; aHR 0.49, 95% CI 0.41-0.58; respectively). Node-positive disease was associated with the highest mortality risk (aHR 2.01, 95% CI 1.80-2.26). Adjuvant chemotherapy was not associated with improved survival among patients with node-negative disease. In the subgroup of patients whose tumors exhibited lymphovascular invasion, when <12 LNs were harvested, chemotherapy was associated with improved survival. This was not observed among patients with 12-23 or ≥24 LNs harvested, though the interaction was not statistically significant.

[CONCLUSIONS] LN harvest is associated with improved survival in node-negative, locally advanced appendiceal adenocarcinoma. While it did not clearly delineate patients benefitting from adjuvant chemotherapy, differential effects by LN harvest may exist in patients with inadequate LN harvest and lymphovascular invasion.