Objectives: Endoscopic local procedures are increasingly applied in patients with superficial esophageal cancer as an alternative to radical oncologic resection. The objective of this article is to determine the risk of nodal metastases in submucosal (sm) esophageal cancer, comparing the two predominating histologic tumor types, squamous cell cancer (SCC) and adenocarcinoma (ADC).
Methods: A query of PubMed, MEDLINE, Embase and Cochrane Library (1980-2009) using predetermined search terms revealed 675 abstracts, of which 485 full-text articles were reviewed. A total of 105 articles met the selection criteria. A review of article references and consultation with experts revealed additional articles for inclusion. Studies that enrolled patients with submucosal esophageal cancer and provided adequate extractable data were included.
Results: The pooled outcomes of 7645 patients with esophageal cancer involving the sm level of infiltration were included in the analysis. Overall, the percentage of lymph node metastasis in submucosal cancer was 37%. Lymph node (N), lymphatic (L) and vascular (V) invasion in sm1 esophageal cancers was 27, 46 and 22%, respectively. Within sm2 lesions, N, L and V invasion were involved in 38, 63 and 38% of patients, respectively. Finally, N, L and V involvement in patients with sm3 lesions was 54, 69 and 47%, respectively. The rates of lymph node metastasis for sm1 and sm2 were higher in SCC compared with ADC, whereas the lymph node metastasis for sm3 was comparable, with >50% involvement in both histologic subtypes. SCC revealed an overall more aggressive behavior compared with ADC (N+: 45 vs 26%; L+: 57 vs 37%; V+: 40 vs 18%).
Discussion: While endoscopic therapy may be adequate in selected patients with 'low-risk' sm1 ADC, submucosal SCC necessitates esophageal resection and systematic lymphadenectomy because of its aggressive nature and tendency for early metastasis.