Watch-and-Wait After Endoscopic Resection for Intermediate-Risk Superficial ESCC: What the Long-Term Data Suggest

When endoscopic resection removes superficial esophageal squamous cell carcinoma, pathology often decides the next clinical question. Is local endoscopic treatment enough, or should the patient undergo additional chemoradiotherapy or surgery to reduce recurrence risk?

This dilemma becomes especially nuanced in patients with pathological T1a–muscularis mucosa esophageal squamous cell carcinoma without lymphovascular invasion. These patients do not fit neatly into the lowest-risk group, but they also do not clearly resemble the high-risk population for whom additional treatment is more routinely considered. The WGO commentary titled “Watch and Wait Works for Intermediate-Risk Superficial Esophageal Cancer” highlights this uncertainty and discusses new long-term data supporting observation as a reasonable approach in selected patients.

The underlying study is “Long-term outcome after endoscopic resection for esophageal squamous cell carcinoma invading muscularis mucosa without lymphovascular invasion: a multicenter retrospective study.” It was published in Gastrointestinal Endoscopy in August 2026, with electronic publication on February 9, 2026. The study was led by Tomohiro Kadota and colleagues and carries the DOI 10.1016/j.gie.2026.02.007.

This was not a randomized trial. It was a multicenter retrospective study from Japan, involving patients with pT1a-MM ESCC without lymphovascular invasion after endoscopic resection. Patients were retrospectively recruited from 47 institutions between 2008 and 2015. The investigators evaluated cumulative recurrence rate, overall survival, and recurrence-free survival.

The Clinical Grey Zone After Endoscopic Cure

Endoscopic resection has become an important treatment for superficial ESCC because it can remove early lesions while preserving the esophagus. The challenge is that endoscopic therapy treats the primary lesion, but pathology must estimate the risk of occult nodal disease or later metastatic recurrence.

Depth of invasion matters. A lesion limited to the epithelium or lamina propria generally carries a different risk profile from a lesion invading more deeply. The group addressed in this study—pT1a-MM without lymphovascular invasion—sits in an intermediate space. The tumor has invaded the muscularis mucosa, but lymphovascular invasion is absent. The WGO commentary notes that previously reported metastatic recurrence rates in this group were 4.3% to 5.6%, placing these patients into an intermediate-risk category rather than a clearly negligible-risk category.

That distinction is clinically important. If the risk is very low, observation avoids unnecessary toxicity and morbidity. If the risk is clinically meaningful, additional therapy might prevent recurrence in some patients. The problem is that the evidence base has historically been limited, especially for large-scale, long-term outcomes. The study explicitly states that the need for additional treatment after ER in this group remains unclear because of the lack of large-scale studies with long-term follow-up.

What the Study Investigated

The study asked a practical question: what happens over the long term to patients with pT1a-MM ESCC without lymphovascular invasion after endoscopic resection?

The study population included 540 patients. After ER, 485 underwent observation, 45 received chemoradiotherapy, and 10 underwent surgery. The exposure of interest was therefore the post-ER management strategy: observation, CRT, or surgery. The outcomes were 5-year cumulative recurrence rate, overall survival, and recurrence-free survival.

This design reflects real-world management rather than randomized allocation. Observation was commonly selected, consistent with community practice. The WGO-linked author summary also notes that, according to guideline context, no clear recommendations had been established regarding additional treatment after ER in this population, and observation had generally been adopted as the community standard approach.

That matters for interpretation. The study does not prove that observation is superior to CRT or surgery. It describes outcomes in patients who underwent different post-ER strategies in a retrospective multicenter setting.

The Main Findings: Low, But Not Zero, Recurrence

The key result is that recurrence after observation was relatively low but not absent.

The reported 5-year cumulative recurrence rates were 4.9% in the observation group, 2.2% in the CRT group, and 10.0% in the surgery group. The corresponding 5-year overall survival rates were 92.7%, 93.3%, and 100%, and the 5-year recurrence-free survival rates were 89.6%, 91.1%, and 90.0%, respectively.

The authors concluded that although cumulative recurrence rate was not negligible, the current strategy of observation may be a reasonable option given the low recurrence risk. This is the central message clinicians should take from the study: observation may be reasonable, but recurrence risk is not zero.

The WGO commentary’s framing of “watch-and-wait” should therefore be read carefully. It does not mean no follow-up. It means avoiding immediate additional treatment in selected patients while maintaining careful surveillance. The author summary specifically notes that the study evaluated outcomes based on periodic and careful follow-up.

Why Observation May Be Reasonable

The clinical argument for observation is straightforward. Additional CRT or surgery may reduce recurrence risk in some patients, but those treatments can also carry morbidity, toxicity, cost, and quality-of-life consequences. For a group with a relatively low absolute recurrence rate, routine escalation for all patients may expose many to treatment who would never recur.

The study’s observation group had a 5-year cumulative recurrence rate of 4.9%. That figure does not make recurrence trivial, especially because recurrent ESCC can be clinically serious. But it does suggest that immediate additional therapy for every patient in this narrowly defined group may not always be necessary.

The author summary states that additional CRT may reduce recurrence risk, but its potential benefit should be weighed against treatment-related toxicity, which may preclude routine use in all patients. This is an appropriately cautious interpretation. A lower recurrence rate in the CRT group cannot be treated as definitive proof of benefit because treatment groups were not randomized and were unequal in size.

The clinical decision therefore remains individualized. The evidence supports observation as a reasonable option in appropriately selected patients, not as a universal mandate.

The Follow-Up Signal: Five Years May Not Be Enough

One particularly relevant finding from the author summary is that five patients developed recurrence more than five years after ER. This point is clinically important because many oncology and endoscopy follow-up conversations become less intensive after the five-year mark.

For pT1a-MM ESCC without LVI, the data suggest that late recurrence can occur. This does not automatically define the ideal surveillance schedule, and the study does not establish a new universal follow-up protocol. However, it supports the idea that surveillance beyond five years may be warranted in some patients.

The author summary also notes that lymph node metastasis is the predominant recurrence pattern in this population and suggests that strategies to improve earlier detection and risk stratification are needed. It mentions more frequent CT surveillance, endoscopic ultrasound, and emerging biomarkers such as circulating tumor DNA as possible future directions. These should be interpreted as research and strategy considerations, not established requirements for every patient.

What This Means for Endoscopists

For endoscopists, the study reinforces the importance of high-quality ER and careful pathology-based risk stratification. The population in the study is highly specific: pT1a-MM ESCC without LVI after ER. Broader conclusions should not be extended to patients with lymphovascular invasion, deeper submucosal invasion, positive margins, clinically evident nodal disease, or other high-risk features.

The study also underscores the importance of multidisciplinary communication. Endoscopists, pathologists, medical oncologists, radiation oncologists, surgeons, and patients may all need to participate in post-ER decision-making. The decision to observe should be active and documented, not a passive absence of further treatment.

Observation also requires infrastructure. Patients need surveillance planning, symptom education, imaging or endoscopic follow-up as clinically appropriate, and clear triggers for reassessment. A watch-and-wait strategy is only as safe as the follow-up system supporting it.

What Clinicians Should Not Conclude

Clinicians should not conclude that observation is proven superior to CRT or surgery. This was a retrospective study, not a randomized comparison. The observation, CRT, and surgery groups were unequal in size, with 485, 45, and 10 patients respectively. The surgery group was especially small, making outcome comparisons difficult.

Clinicians should also not conclude that recurrence risk is negligible. The authors explicitly state that cumulative recurrence rate was not negligible, even though observation may be reasonable given the low recurrence risk. That distinction is essential for patient counseling.

The findings should not be generalized to all superficial ESCC after ER. They apply to the study-defined group: pT1a-MM ESCC without LVI after endoscopic resection. Patients with LVI, pT1b disease, positive vertical margins, or suspected nodal disease represent different clinical scenarios and require separate evidence and guideline interpretation.

Strengths and Limitations

The major strength of this study is its scale and multicenter design. The study included 540 patients from 47 institutions, addressing an evidence gap created by earlier smaller or single-center datasets. The long-term focus is also clinically valuable because recurrence may occur beyond standard short follow-up windows.

The limitations are equally important. The study was retrospective. Treatment selection was not randomized. The groups were imbalanced, especially the surgery group. The study was conducted in Japan, within a healthcare and endoscopy context where expertise in ESCC detection, ER, pathology, and surveillance may differ from other regions. Therefore, implementation in other settings should account for local endoscopic expertise, pathology quality, follow-up adherence, and patient preferences.

Another limitation is that the accessible abstract and commentary do not provide all granular details needed for protocol-level adoption. For example, they do not establish a definitive surveillance interval or a validated risk model for selecting patients who should receive CRT rather than observation.

Future Research Questions

The study clarifies that observation can be reasonable, but it also points toward the next research agenda. Clinicians need better tools to identify which patients within this intermediate-risk category are most likely to recur. The author summary highlights the need for earlier detection and improved risk stratification, including possible roles for more frequent CT surveillance, EUS, and circulating tumor DNA.

Future studies should examine whether selected patients benefit from additional CRT, whether surveillance intensity can be individualized, and whether biomarkers can identify occult recurrence risk before imaging or clinical recurrence. Prospective studies or carefully designed comparative analyses would be particularly useful, although randomized trials may be difficult in this narrow clinical subgroup.

Clinical Takeaway

For patients with pT1a-MM ESCC without lymphovascular invasion after endoscopic resection, this Japanese multicenter retrospective study supports observation as a reasonable post-ER strategy, provided follow-up is careful and long term. The 5-year recurrence risk in the observation group was low but not negligible, and late recurrences beyond five years were reported.

The GastroAGI interpretation is cautious: this is practice-informing observational evidence, not a definitive treatment algorithm. It supports shared decision-making and structured surveillance rather than automatic escalation or complacent discharge.

Five Key Clinical Takeaways

1. The evidence comes from a multicenter retrospective Japanese study, not a randomized trial.

2. The study population was specific: patients with pT1a-MM ESCC without lymphovascular invasion after endoscopic resection.

3. Among 540 patients, 485 were observed, 45 received CRT, and 10 underwent surgery.

4. The 5-year cumulative recurrence rate was 4.9% with observation, supporting observation as reasonable but not risk-free.

5. Late recurrence beyond five years was reported, so watch-and-wait should mean structured long-term surveillance, not minimal follow-up.

Source Reference and Link

Kadota T, Kawachi H, Fujii S, Yoshio T, Abe S, Nagami Y, et al. Long-term outcome after endoscopic resection for esophageal squamous cell carcinoma invading muscularis mucosa without lymphovascular invasion: a multicenter retrospective study. Gastrointestinal Endoscopy. 2026;104(2):286–292. Published online February 9, 2026. DOI: 10.1016/j.gie.2026.02.007.

Related commentary: World Gastroenterology Organization. “Watch and Wait Works for Intermediate-Risk Superficial Esophageal Cancer.”