Initial experience of individualized chemoradiotherapy for superficial esophageal cancers based on the sentinel lymph node concept

Background: Esophageal squamous cell carcinomas (ESCCs) invading the muscularis mucosae (T1a-MM) cause subclinical node metastasis in approximately 10 % of cases. When chemoradiotherapy (CRT) is administered to T1a-MM or deeper ESCC, prophylactic irradiation of areas with a risk of subclinical nodal metastasis may improve disease control. We had an opportunity for clinical observation of the status of lymph nodes in the patients whose hot spots in lymphoscintigraphy before CRT had been included within the irradiation field. Methods: We retrospectively investigated patients selected using following criteria: (1) cT1a-MM and cT1b without previous treatments, or pT1a-MM and pT1b cancers proved by previous endoscopic resections; (2) patients with neither clinical nodal nor distant metastasis; (3) patients whose hot spots detected by lymphoscintigraphy had been included within the irradiation fields. Lymphoscintigraphy had been examined with endoscopic injection of a radioisotope around the primary lesion before CRT. Results: Sixteen patients met the inclusion criteria. Of these patients [T1a-MM (4 cases), T1b-SM1 (2 cases), and T1b-SM2 (10 cases)], there were 9 definitive CRTs and 7 adjuvant CRTs after endoscopic resections. The median dose of irradiation was 60 Gy to the primary tumors and 46 Gy to the hot spots. All patients with definitive CRT achieved complete remission. At the median follow-up of 76.6 months, there was no lymph node recurrence. Conclusions: Prophylactic irradiation of the hot spots in lymphoscintigraphy may be effective. This result warrants further evaluation concerning the validity of irradiation field settings based on lymphoscintigraphic findings in patients with superficial ESCCs.