Extent of Lymphadenectomy in Esophageal Cancer: How Many Lymph Nodes Is Enough?

Excerpt

There is no question that presence of lymph node (LN) metastasis in esophageal cancer is one of the most powerful prognostic indicators. Multiple studies have demonstrated that patients with lymph node metastasis have more aggressive tumor biology, higher rates of locoregional and distant recurrence, and hence, worse survival. Esophageal cancer staging according to the sixth edition of the tumor–node–metastasis (TNM) staging manual of the American Joint Committee on Cancer (AJCC) uses only the location of the involved LN or the distance from the primary tumor for nodal disease staging (i.e., N1 versus M1a).1 This method tends to group patients with very different disease burden and biologic behavior into a similar stage, resulting in a less powerful staging system. More recent studies have explored the impact of LN metastases further, and investigators seem to agree that it is not only a question of the presence or absence of nodal disease, but more importantly, how many LN are involved with disease.2,3 Rizk and colleagues reported that the prognosis of patients after esophagectomy worsens significantly after four or more lymph nodes have metastases, irrespective of T stage.3 LN subclassification according to nodal groupings showed differences in survival curves, and better prognostic stratification can be obtained to facilitate treatment decisions. The Worldwide Esophageal Cancer Collaboration has reported with tremendous effort an international and multi-institutional dataset that refined the recommendations for the revised esophageal cancer staging system and incorporates the important factor of extent of nodal disease.4 After these and other studies highlighted the importance of lymph node subclassification, the upcoming seventh edition of the AJCC TNM staging manual has incorporated these changes into a more robust esophageal cancer staging system.5 The new staging will have three groups of positive nodal disease (N1, 1–2 regional LN; N2, 3–6 regional LN; N3, more than 7 metastatic LN).5 The need for more detailed nodal analysis now puts the pressure on performing a thorough and adequate lymphadenectomy during esophagectomy in order to ensure an accurate nodal stage, but what is the optimal extent of lymphadenectomy for esophageal cancer to ensure adequate LN clearance and avoid understaging the disease? Does a more radical lymphadenectomy confer a survival advantage, or is the improved survival an effect of stage migration? Is a more radical lymphadenectomy also necessary in cases where chemoradiation therapy is also administered? …