Effect of chemoradiation on the development of second primary cancers after endoscopic resection of T1 esophageal squamous cell carcinoma

Background Patients with early esophageal squamous cell carcinoma (ESCC) may develop multiple second primary ESCC and cancers in other organs even after curative endoscopic resection (ER). We investigated whether administration of chemoradiotherapy (CRT) after ER decreases the incidence of second primary cancers. Methods We conducted a post hoc analysis of the prospective study. Among the registered 170 patients with clinical submucosal ESCC, 74 underwent ER alone, and 96 underwent ER followed by CRT (ER + CRT) because of pathological results of submucosal or lympho-vascular invasion. We compared the incidence of second primary cancers in esophagus and in other organs between two treatment groups. A univariate analysis was performed to investigate the related risk factors. All patients were followed up with esophagogastroduodenoscopy and CT every 4 months for the first 3 years and every 6 months thereafter. Results Sixty-one ESCC were detected in 32 patients, and the 3-year cumulative incidence of multiple ESCCs was not different between ER + CRT and ER alone (10.4% vs. 13.5%). Sixty-three second primary cancers in other organs were detected in 45 patients, and there was no difference in the cumulative incidence between two groups. The risk factors for multiple ESCCs were high alcohol consumption and grade C multiple Lugol-voiding lesions. Heavy drinker or patients with grade C multiple Lugol-voiding lesion rather than CRT were at risk for second primary ESCC. Conclusion CRT after ER did not decrease the cumulative incidence of second primary ESCC nor cancers in other organs comparing with ER alone.