The minimum number of lymph nodes to be examined during pancreaticoduodenectomy (PD) for patients with ampullary adenocarcinoma (AC) is still debatable due to limited clinical data. Therefore, here we explored the relationship between the number of examined lymph node (ELN) and the current N staging (American Joint Committee on Cancer staging system, AJCC, 8 edition) after PD for AC as well as determined the minimum number of examined lymph nodes (MNELN) to ensure the accurate detection of nodal involvement. Patients underwent PD for AC in the National Cancer Center cohort of China (NCC cohort of China) from 1998 to 2020 and in the Surveillance, Epidemiology, and End Results database (SEER database) from 2010 to 2018 were retrospectively reviewed, and a total of 452 eligible patients were included in this study. The MNELN was evaluated by binomial probability law and best survival separation methods. Furthermore, the cut-off value of MNELN was validated in the NCC cohort of China using Least Absolute Shrinkage and Selection Operator (LASSO) regression. Our analysis indicated that the median number of ELN was 14, and the number of ELN was positively correlated with N stage. The MNELN was 16, whereas the best survival separation of ELN was 38 in node-positive patients and 3 in node-negative patients. In the validation cohort, the number of 16 ELNs was identified as a predictive variable for lymph node metastasis with nonzero coefficients in the LASSO-logistic regression model. Together, we concluded that a greater number of ELN was associated with more accurate nodal status assessment in PD for AC patients. A minimum of 16 lymph nodes were required to during PD in AC patients.
Keywords: Examined lymph node; ampullary adenocarcinoma; pancreaticoduodenectomy; stage migration.
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