Intraoperative diagnosis of lymph node metastasis in non-small-cell lung cancer by a semi-dry dot-blot method

OBJECTIVES Sublobar resection procedures, such as segmentectomy and wedge resection, can be used for resectable lung cancer when the cancer is small or the condition of the patient is poor. In such cases, intraoperative lymph node (LN) exploration is necessary to avoid incomplete resection of potential N1 or N2 disease. The semi-dry dot-blotting (SDB) method was developed to detect intraoperative LN metastasis as a quick, cost-effective procedure that does not require special technical expertise. This study examined whether SDB can sufficiently identify LN metastasis in lung cancer patients. METHODS This study prospectively examined 147 LNs from 50 lung cancer patients who underwent surgery at Nagasaki University Hospital between April 2011 and June 2013. The SDB method uses antigen–antibody reactions with anti-pancytokeratin as the primary antibody and detects cancer cells using chromogen. To identify LN metastases, each LN was examined by the SDB method during surgery along with intraoperative pathological diagnosis (ope-Dx) and permanent pathological diagnosis (permanent-Dx). RESULTS Compared with permanent-Dx, SDB offered 94.7% sensitivity, 97.7% specificity and 97.2% accuracy, while ope-Dx exhibited 84.2% sensitivity, 100% specificity and 98.0% accuracy. For 3 cases, micrometastases were detected by the SDB method but not by ope-Dx. Three LNs from lobar stations showed pseudo-positive results by the SDB method because of the presence of alveolar epithelium. CONCLUSIONS The SDB method offers acceptably high accuracy in detecting LN metastasis, especially for mediastinal LNs, and represents a potential alternative for the intraoperative diagnosis of LN metastasis, even in the absence of a pathologist.