Adjuvant Radiotherapy for pT1b Esophageal Cancer After Submucosal Endoscopic Resection

The incidence of early-stage esophageal cancer (EC) is increasing rapidly and even accounting for approximately 40% of esophageal squamous cell carcinoma. Endoscopic Resection (ER) is a crucial therapeutic and diagnostic method for superficial esophageal cancer. However, lymph node metastasis rate in pT1b patients is relatively high, and additional treatment is recommended after ER.

Adjuvant chemoradiotherapy is a treatment option and has already been proven to be equivalent to radical surgery. However, limited studies, with relatively small sample size and nature of low-level evidence, consistently showed that additional adjuvant radiotherapy failed to improve survival. Hence, adjuvant radiotherapy should not be applied without selection.

T1b EC patients are a heterogeneous population, with reported regional metastasis or recurrence rates varying considerably from 0-53% in SM1 disease, 19-31% in SM2, and 36-61% in SM3. The risk factors of regional metastasis or recurrence were also reported, generally including lymphovascular invasion (LVI) and pT1b disease.

In view of the aforementioned evidence, we hypothesized that selective adjuvant radiotherapy based on risk factors might significantly improve survival. The aim of this study was to evaluate the efficacy of adjuvant radiotherapy after ESD for pT1b EC and further explore the potential population who could benefit.

Inclusion criteria

(1) ECOG score < 2; (2) Pathologically confirmed squamous or adenosquamous cell cancer; (3) Clinical stage cTis-1bN0M0; (4) Multiple primary T1 lesions were allowed; (5) No lymph nodes and distant metastases confirmed by chest CT, neck CT or neck ultrasound, and abdominal CT or abdominal ultrasound; (6) Underwent ESD between January 2010 and December 2019; (7) pT1b disease confirmed by endoscopically resected specimen; (8) Underwent adjuvant radiotherapy (with or without chemotherapy) or surveillance after ESD.

Exclusion criteria

(1) Diagnosed with other locally-advanced or advanced malignancies within 3 years before ESD; (2) Underwent radical surgery after ESD; (3) Upfront radiotherapy, chemotherapy or chemoradiotherapy before ESD; (4) Lost to follow-up or insufficient clinical information.