Is it justified to ablate flat-type esophageal squamous cancer? An analysis of endoscopic submucosal dissection specimens of lesions meeting the selection criteria of radio frequency studies

Background: Endoscopic radiofrequency ablation (RFA) appears to be a safe and effective treatment for flat-type noninvasive squamous neoplasia of the esophagus. However, if RFA is applied to lesions containing invasive cancer (esophageal squamous cell carcinoma [ESCC]), histological features associated with lymph node metastases may remain undetected. In addition, extension of neoplasia down the ducts of esophageal submucosal glands (SMGs) may create a sheltered niche beyond the reach of ablation. Objective: To determine the RFA eligibility of flat-type ESCC. Design: Retrospective analysis of prospectively collected data of ESCC patients. Setting: National Cancer Center Hospital, Tokyo, Japan. Patients: Patients with flat-type ESCC larger than 3 cm removed by endoscopic submucosal dissection (ESD). Interventions: Three endoscopists involved in RFA studies in China reviewed endoscopic images to select lesions eligible for RFA. Corresponding ESD resection specimens were histologically examined. Main Outcome Measurements: The presence of poor histological features (ie, invasion in m3 or deeper, poor tumor differentiation, or lymphovascular invasion) and the number of involved esophageal SMGs and ducts. Results: Sixty-five lesions were included, 17 (26%) of which qualified as RFA eligible by RFA endoscopists. Interobserver agreement for this assessment was poor (k = 0.09). Six of the 17 specimens (35%) showed relevant disease: 4 lesions invaded in the muscularis mucosae, 1 of which also showed lymphovascular invasion; 2 lesions showed extension of neoplasia into SMGs. Limitations: Limited number of cases. RFA eligibility status was based on analysis of still images. Conclusions: One third of flat-type ESCC, deemed eligible for RFA, demonstrated histological features that are considered (relative) contraindications to endoscopic treatment. Because it appears difficult for endoscopists to identify low-risk ESCC, conservative use of RFA for flat-type ESCC is advocated until long-term follow-up data are available.