7 Background: Extended radical esophagectomy with three-field lymph node dissection has been recognized as the standard procedure for thoracic esophageal cancer in Japan, even for clinically T1N0 cases. However, to eliminate the uniform application of the highly invasive surgery, we hypothesized that sentinel lymph node (SLN) mapping would play a key role to obtain individual information and allows modification of the surgical procedure for early esophageal cancer. Methods: We have established radio-guided method to detect SLNs in patient with early esophageal cancer using endoscopic injection of technetium-99m tin colloid. Preoperative lymphoscintigraphy and intra-operative use of hand held gamma probe were reliable to locate the radioactive SLNs. Intra-operative gamma probing was also feasible in thoracoscopic or laparoscopic surgery using a special gamma detector which is introducible from trocar ports. Results: SLN mapping has been performed for 70 patients with clinically N0 and early (pT1) esophageal cancer in our institute since 1999. Detection rate of hot node using our procedure was 94% (66/70). The mean number of sentinel nodes per case was 4.6. Twenty-one of 23 cases (91%) with lymph node metastasis showed positive SLNs. Accuracy of metastatic status based on SLN was 97% (64/66). SLNs widely spread from cervical to abdominal areas. In more than 80% of the cases, at least one SLN was located in the 2nd or 3rd compartment of regional lymph nodes. However, 56 (85%) of 66 patients had no lymph node metastasis or metastasis (+) only in SLNs. Conclusions: Our results suggest that SLN concept for clinically N0 and T1 esophageal cancer could be validated. Theoretically more than 80% of patients with pT1b esophageal cancer may be controlled by local treatments such as surgery and chemoradiotherapy targeting primary tumors plus their SLNs. Individualized selective and modified lymphadenectomy targeted on SLN basins for clinically N0 early esophageal cancer should become feasible and clinically useful as less invasive surgical procedures.
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