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Introductıon
Lung cancer is the leading cause of cancer-related morbidity and mortality among men and women worldwide [1]. Despite significant progress in lung cancer management, including diagnostic approaches, biomarkers and treatments, it remains challenging to diagnose lung cancer until advanced stages [1]. The International Association for the Study of Lung Cancer (IASLC) Staging and Prognostic Factors Committee has recently demonstrated significant survival differences among patients with pN0, pN1 and pN2 non-small cell lung cancer (NSCLC), based on an international database used to update the TNM staging system [2]. The anatomical location of metastatic lymph nodes (LNs)—the basis of the current N staging system—is crucial, as lymphatic spread is believed to follow a stepwise pattern along lymphatic drainage pathways. Furthermore, the well-established N staging system is closely linked to treatment strategies in NSCLC patients [3]. Several studies have shown that lymph node metastasis is associated with an increased risk of multi-organ metastasis in NSCLC patients [4]. It has been a subject of considerable debate whether cancer cells in lymph nodes can seed distant organs [4]. As lymph nodes are often the first site of metastasis, it is also possible that lymphatics serve as part of the pathway contributing to the subsequent dissemination to distant organs [5]. Molecular testing is now recommended at the time of diagnosis to elucidate tumor pathogenesis and to guide targeted therapies beyond conventional chemotherapy. According to updated National Comprehensive Cancer Network (NCCN) guidelines, routine molecular testing is recommended for NSCLC patients to detect alterations in ALK, ROS1, EGFR, KRAS/NRAS, BRAF, RET, MET, ERBB2 and PD-L1 genes [6, 7]. A number of studies have shown that the EGFR, MAPK (mitogen-activated protein kinase) and PI3K (phosphoinositide 3-kinase) signaling pathways play a critical role in tumor metastasis [8, 9]. It would be valuable to evaluate TP53, KRAS and PTEN mutations that are involved in these pathways and seen in NSCLC. Therefore, characterizing as much of the tumor’s gene profile as possible, rather than just looking at specific mutations, will be more effective in understanding pathogenesis and determining treatment [7].
Considering the critical clinical importance of lymph nodes, we think that determining the metastasis status and molecular biomarkers of lymph nodes and revealing the relationship between them may contribute to the literature to understand the pathogenesis...