Assessment of sentinel node concept in esophageal cancer based on lymph node micrometastasis

Purpose: The clinical significance of lymph node micrometastasis remains unclear in patients with esophageal cancer. Therefore, accurate assessment of lymph node status including micrometastasis is important when performing sentinel node (SN) navigation surgery. The purpose of the present study was to investigate the adequacy of SN concept based on lymph node micrometastasis determined by immunohistochemistry (IHC) and reverse transcription-polymerase chain reaction (RT-PCR) in patients with esophageal cancer. Methods: A total of 57 patients with esophageal cancer who were preoperatively diagnosed as having T1-T2 (cT1-T2) and N0 (cN0) were enrolled. They underwent standard esophagectomy with lymph node dissection. One day before surgery, a total of 3 mCi of ^99mTechnetium-tin colloid was endoscopically injected into the submucosa around the tumor. During the operation, radioisotope uptake in the lymph nodes was measured using Navigator GPS. All dissected lymph nodes were investigated by RT-PCR using the double marker of CEA and SCC, hematoxylin-eosin (HE) staining, and IHC. Results: Node-positive incidence identified by HE and IHC was 12.3 % (7/57) and 19.3 % (11/57), respectively. RT-PCR demonstrated micrometastasis in four of 46 patients without nodal metastasis determined by HE staining and IHC. No non-SN metastases were found in 42 patients without micrometastasis identified by IHC and RT-PCR of SN. Accuracy and false negative rates were 100 % (57/57) and 0 % (0/42), respectively. Conclusions: SN concept might be acceptable in patients with cT1-T2 and cN0 esophageal cancer, even in the presence of micrometastasis identified by IHC and RT-PCR.