Comparisons of minimally invasive esophagectomy and open esophagectomy in lymph node metastasis/dissection for thoracic esophageal cancer

Background: The study aimed to clarify the characteristics of lymph node metastasis (LNM) and to compare the oncologic outcomes of minimally invasive esophagectomy (MIE) with open esophagectomy (OE) in terms of lymph node dissection (LND) in thoracic esophageal cancer patients.Methods: The data from esophageal cancer patients who underwent MIE or OE from January 2016 to January 2019 were retrospectively reviewed. The characteristics of LNM in thoracic esophageal cancer were discussed, and the differences in numbers of LND, LND rate, and LNM rate/degree of upper mediastinum between MIE and OE were compared.Results: For overall characteristics of LNM in 249 included patients, the highest rate of LNM was found in upper mediastinum, while LNM rate in middle and lower mediastinum, and abdomen increased with the tumor site moving down. The patients were divided into MIE (n = 204) and OE groups (n = 45). In terms of number of LND, there were significant differences in upper mediastinum between MIE and OE groups (8 [5, 11]vs. 5 [3, 8],P < 0.001). The comparative analysis of regional lymph node showed there was no significant difference except the subgroup of upper mediastinal 2L and 4L group (3 [1, 5]vs. 0 [0, 2],P < 0.001 and 0 [0, 2]vs. 0,P = 0.012, respectively). Meanwhile, there was no significant difference in terms of LND rate except 2L (89.7% [183/204]vs. 71.1% [32/45],P = 0.001) and 4L (41.2% [84/204]vs. 22.2% [10/45],P = 0.018) groups. For LNM rate of T3 stage, there was no significant difference between MIE and OE groups, and the comparative analysis of regional lymph node showed that there was no significant difference except 2L group (11.1% [5/45]vs. 38.1% [8/21],P = 0.025). The LNM degree of OE group was significantly higher than that of MIE group (27.2% [47/173]vs. 7.6% [32/419],P < 0.001), and the comparative analysis of regional LNM degree showed that there was no significant difference except 2L (34.7% [17/49]vs. 7.7% [13/169],P < 0.001) and 4L (23.8% [5/21]vs. 3.9% [2/51],P= 0.031) subgroups.Conclusion: MIE may have an advantage in LND of upper mediastinum 2L and 4L groups, while it was similar to OE in other stations of LND.