Risk-stratified clinical management of superficially invasive esophageal squamous cell carcinoma after endoscopic resection: finding the sweet spot

term outcomes of a risk-stratified management approach for patients with superficially invasive esophageal squamous cell carcinoma (ESCC) [1]. The key factor driving management decisions for superficial ESCC after endoscopic resection is depth of tumor invasion, as this is linked to the risk of lymph node metastasis (LNM) in these patients [2, 3]. For in situ ESCC (stage T1a-M1) and ESCC limited to the lamina propria (T1a-M2), the risk of co-incident LNM is estimated to be less than 5%. This marginal risk is deemed acceptable for endoscopic therapy, given the morbidity and mortality associated with esophageal resection. For lesions invading the muscularis mucosae (T1aMM), the risk of co-incident LNM has been variously reported as 0%–9%, whereas the LNM risk for lesions infiltrating the superficial submucosa (< 200 μm from the muscularis mucosae, stage T1b-SM1) has been reported to lie between 8% and 16% [4–6]. These superficially invasive ESCC lesions (stage T1a-MM and T1b-SM1) have therefore been considered a “borderline” indication for endoscopic treatment, where management should be individualized and discussed in a multidisciplinary setting in centers with a tertiary referral service for esophageal cancer. However, these data on LNM risk for stage T1a-MM and T1bSM1 ESCC have been derived from retrospective histopathologic analyses of resection specimens, which do not reveal the natural history of conservatively treated superficially invasive ESCC. Indeed, studies have suggested that long-term survival of patients with ESCC lesions infiltrating the muscularis mucosae without further poor prognostic indicators, such as lymphovascular invasion (LVI) or poor tumor differentiation, is excellent (> 95% tumor-specific survival) [7, 8]. As a result, there is now a move toward expanding the eligibility criteria for endoscopic therapy to include ESCC patients with infiltration of the muscularis mucosae and superficial submucosa who lack poor prognostic indicators, so-called low-risk disease [3, 9].