Circumferential resection margin in esophageal cancer.

In 1993, Sagar et al reported that microscopic involvement of the circumferential resection margin (CRM) is related to local recurrence and decreased survival. Since then, the role of the CRM in esophageal cancer has been extensively investigated in the literature. Dexter et al in 2001 found in their study, which included 135 patients with esophageal cancer, that 64 patients (47%) were positive CRM and the presence of tumor within 1 mm of the CRM is an independent prognostic factor for esophageal cancer. In 2006, Griffiths et al also reported that CRM involvement predicted poor prognosis in patients with resected esophageal cancer. In a recent study focusing on the significance of CRM involvement in 94 patients who underwent neoadjuvant chemoirradiation followed by surgery, Liu et al concluded that the involvement of CRM is a significant risk factor of survival. Of these 94 patients with squamous cell carcinoma of the esophagus, 17 had positive CRM and 7 had T4 tumor. However, in contrast to these reports, some authors have suggested that CRM is not a prognostic predictor in esophageal cancer. The most important predictors of esophageal cancer prognosis include the overall TNM stage, completeness of resection (R classification), and status of lymph node metastasis. Prior to discussing the importance of CRM in esophageal cancer, the relationship between residual disease classification and CRM should be clarified. The residual tumor classification is a strong prognostic factor after surgical resection in esophageal cancer. It is defined such that R0 is complete microscopic and macroscopic resection, R1 is residual microscopic disease, and R2 is macroscopic disease. Usually, the CRM is defined as the surgically cut surface of the connective tissues that encase the esophagus. To investigate the significance of CRM in the prognosis of the patients with esophageal cancer, patients with incomplete resection should not be included. In the assessment of CRM in esophageal cancer specimens, according to the College of American Pathologists (CAP), the R1 category is considered to include only tumors positive at the cut margin of resection. However, the Royal College of Pathologists (RCP) considered that the R1 category as tumor is located within 1 mm of the cut margin. Most studies investigating the association between CRM involvement and survival in esophageal cancer did not address the differences between the CRM definitions of these two schools. In 2009, Deeter et al analyzed 135 patients with T3 esophageal cancer. They found that positive margins were