Abstract
Simple SummaryDue to the rising burden of pancreatic cancer and poor outcomes, a precise, post-operative cancer staging for further and individualized therapy is needed. In the latest cancer classification system, the lymph node invasion mechanism is not addressed. Due to different outcomes regarding the lymph node invasion, we suggest a rethinking of the current system. Mechanisms of lymph node invasion seem to play a prognostic role in pancreatic ductal adenocarcinoma (PDAC) after resection. However, the 8th edition of the TNM classification of the American Joint Committee on Cancer (AJCC) does not consider this. The aim of this study was to analyse the prognostic role of different mechanisms of lymph node invasion on PDAC. One hundred and twenty-two patients with resected PDAC were examined. We distinguished three groups: direct (per continuitatem, Nc) from the main tumour, metastasis (Nm) without any contact to the main tumour, and a mixed mechanism (Ncm). Afterwards, the prognostic power of the different groups was analysed concerning overall survival (OS). In total, 20 patients displayed direct lymph node invasion (Nc = 16.4%), 44 were classed as Nm (36.1%), and 21 were classed as Ncm (17.2%). The difference in OS was not statistically significant between N0 (no lymph node metastasis, n = 37) and Nc (p = 0.134), while Nm had worse OS than N0 (p < 0.001). Direct invasion alone had no statistically significant effect on OS (p = 0.885). Redefining the N0 stage by including Nc patients showed a more precise OS prediction among N stages (p = 0.001 vs. p = 0.002). Nc was more similar to N0 than to Nm; hence, we suggest a rethinking of TNM classification based on the mechanisms of lymph node metastases in PDAC. Overall, this novel classification is more precise.
Highlights
According to the International Agency for Research on Cancer, more than 495,000 new cases of pancreatic cancer were recorded worldwide in 2020
Our study provides data that support a redefinition of the N stage by including the mechanism of lymph node involvement [12]
According to the involved lymph node mechanisms, we found 20 (16.4%) patients with direct lymph node invasion (Nc), 44 (36.1%) patients with lymph node metastasis without any contact with the tumour (Nm), and 21 (17.2%) patients showing mixed lymph node invasion (Ncm) (Figure 1)
Summary
According to the International Agency for Research on Cancer, more than 495,000 new cases of pancreatic cancer were recorded worldwide in 2020. Previous studies [7,8,9,10,11,12] have analysed the mechanisms of lymph node invasion and compared the prognosis of direct lymph nodes from the main tumour through cancer related angiogenesis and immunosuppression via crosstalk between the cancer endothelium and the surrounding microenvironment and lymph node metastasis without any contact with the main tumour [13,14] These small studies showed that the mechanisms underlying lymph node invasion may have effects on the survival rate, the data are contradictory [7,8,9,10,11,12].
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