Measurement of the tumor invasion depth into the submucosa in early adenocarcinoma of the esophagus (pT1b): Can microns be the new standard for the endoscopist?

Abstract

Endoscopic resection (ER) has widely been established as a curative treatment approach in earlystage adenocarcinoma of the esophagus (EAC) limited to the mucosa (pT1a). The first report dates back to the year 2000. In the meantime, several studies have been able to show that ER is effective and safe also in the long-term follow-up (FU). Esophagectomy has been the previous gold standard for EAC. In contrast to the organ-preserving approach of ER, it carries a mortality risk of at least 2%–5%. Morbidity of surgery ranges from 20% to 50%. That is why ER has gained importance during the last years. There are two prerequisites for any kind of endoscopic treatment with a curative intent in EAC: First, the target lesion should have a very low risk of lymphnode (LN) metastasis. In contrast to esophagectomy, the LNs remain in place during endoscopic treatment. Second, endoscopic therapy should be effective and safe also in the long term. Only by long-term FU can extraesophageal tumor recurrence be ruled out. According to studies, both conditions are fulfilled for mucosal EAC. But what is the situation regarding EAC with invasion beyond the muscularis mucosae into the submucosal (sm) layer (pT1b EAC)? It is known that the overall risk of LN metastasis in pT1b lesions is higher than in mucosal EAC. However, the LN risk needs to be looked at from a more differentiated aspect: If the invasion depth into the submucosa is pragmatically divided in equal thirds (sm1/2/3), the rate of LN metastasis has been shown to depend on the depth of invasion. The risk of LN metastasis ranges from 0 to 20% in case of incipient sm invasion (pT1b sm1). Getting into even more detail, it has been reported that among pT1b sm1 EAC lesions there is a favorable histological pattern along with a very low risk of LN metastasis in accordance with the LN rates known from pT1a EAC. Endoscopic therapy for pT1b EAC