Definitive-dose adjuvant radiotherapy following endoscopic submucosal dissection for superficial esophageal cancer.

Background: Prophylactic chemoradiation therapy (CRT) using 40-41.4 Gy post-endoscopic submucosal dissection (ESD) for clinical T1N0M0 esophageal cancer reportedly yields favorable outcomes. However, it cannot completely prevent locoregional lymph node (LN) metastases. We retrospectively analyzed outcomes and adverse events associated with our dose-escalated treatment regimen (definitive-dose radiotherapy [RT] of 50-61.2 Gy, with/without chemotherapy) for these patients, and predictors of progression-free survival (PFS) and overall survival (OS).

Methods: Between 2006 and 2018, 44 consecutive patients (42 men and 2 women; median age, 70 years) who underwent definitive-dose RT post-ESD and had a pathological depth of the muscularis mucosa with lymphovascular invasion (LVI) or the upper-middle submucosal third at our institution were included. We excluded patients who could not obtain a margin-free resection by ESD. If feasible, systemic chemotherapy with 5-fluorouracil plus high- or low-dose cisplatin or nedaplatin was administered concurrently.

Results: Five-year PFS, OS, and disease-specific survival rates were 78.8%, 88.4%, and 97.7%, respectively. Six metachronous esophagus (14%), two locoregional LN within the irradiated area with a prophylactic dose of 41.4 Gy (5%), and two locoregional LN plus liver (5%) recurrences occurred. No LN recurrence occurred within the definitive dose of ≥ 50 Gy in the irradiated area. Metachronous esophageal recurrence involved areas receiving ≥ 50 Gy. Univariate and multivariate analyses revealed that age was an independent prognostic factor for both PFS and OS.

Conclusions: Definitive-dose RT/CRT post-ESD could provide favorable locoregional LN control and PFS/OS regardless of patient characteristics, including pathological findings and chemotherapy regimen/course, except for age. These results need to be interpreted carefully given several limitations, therefore, definitive-dose RT/CRT should be conducted with caution in clinical practice until high-quality prospective clinical trials evaluating the effectiveness and safety.