<qa>  What is the critical factor to determine if a patient is considered as a surgical candidateAssessment of lymph nodes LNs for invasion by metastasis is undertaken if patient management is influenced by a positive or negative result. In non-small cell lung cancer NSCLC, mediastinal LN invasion by malignant cells is a critical factor to determine if a patient is considered as a surgical candidate or not.2 In esophageal cancer, LN metastasis may be found in the mediastinum, the neck and the abdomen.4 Invasion of these LNs must be considered in the selection of treatment of esophageal cancer.3,4 