ALCAM and esophageal squamous cell carcinoma: CD166 is an activated leukocyte cell adhesion molecule (ALCAM), with a controversial role in cancer: immunohistochemical studies on melanocytic lesions showed that CD166 overexpression was associated with tumor progression [26], as well as in bladder cancer with stage/grade [27] and in esophageal squamous cell carcinoma with poor prognosis [28].