Clinical necessity of the immunohistochemical reassessment of para-aortic lymph nodes in resected pancreatic ductal adenocarcinoma

Para-aortic lymph node (PALN) metastasis is widely regarded as a systemic disease in cancer. Undetected PALN micrometastases during routine hematoxylin and eosin (HE) staining may be a cause of poor prognosis following a potentially curative pancreatectomy for pancreatic cancer. In the present study, paraffin-embedded PALN tissue blocks from 99 patients who underwent a pancreatectomy were re-evaluated by immunohistochemical staining using cytokeratin (CK)-19. Patients with PALN metastasis were summarized according to the clinicopathological data. A total of 484 PALNs (median, 4.9 nodes per patient; range, 1-19) were evaluated. PALN metastases were revealed in eight patients (8.1%) by routine HE staining of frozen section biopsies and in one patient (1.0%) by HE staining of a permanent section. Only one patient (1.0%) demonstrated micrometastasis by IHC; this patient did not display any adverse pathological characteristics and had a relatively favorable survival period of 41 months. The present study concluded that an additional reassessment for micrometastasis in PALNs using CK-19 immunohistochemistry (IHC) is not a viable method for determining the survival outcome. A careful examination of a frozen section biopsy is sufficient for attempting curative surgery.