Prognostic Impact of Para-Aortic Lymph Node Micrometastasis in Pancreatic Ductal Adenocarcinoma

Background It is still unclear whether micrometastasis of para-aortic lymph nodes (PALNs) in pancreatic ductal adenocarcinoma (PDAC) is tantamount to PALN metastasis detected by hematoxylin and eosin (HE) staining. Methods A total of 242 patients with PDAC who underwent radical pancreatectomy with PALN dissection were eligible for this study. Micrometastasis in PALNs was evaluated by CAM 5.2 immunohistochemistry. The relationship between PALN status and overall survival (OS) was analyzed. Results Of the 242 enrolled patients, 25 (10 %) had PALN metastasis detected by HE (PALN HE-positive), and 21 (9 %) had PALN micrometastasis not detected by HE but identified by CAM 5.2 immunohistochemistry. Univariate analysis revealed that patients with PALN micrometastasis ( p = .004) and PALN HE positivity ( p = .003) had a significantly shorter OS than those without PALN metastasis, whereas no significant difference was observed between the two former groups ( p = .874). In multivariate analysis, lack of adjuvant chemotherapy (hazard ratio [HR] 2.43, p < .001), PALN micrometastasis (HR 1.89; p = .046), and PALN HE-positivity (HR 1.89, p = .023) were identified as independent risk factors for poor prognosis. Within a subset of 46 patients with PALN HE-positivity or micrometastasis, lack of adjuvant chemotherapy was independently associated with poor OS (HR 2.58. p = .029). Conclusions The prognosis of patients with PALN micrometastasis was extremely poor as well as HE-positive PALNs. However, postoperative adjuvant chemotherapy may contribute to improving the prognosis of PDAC patients with PALN metastasis.