Significance of para-aortic lymph node dissection for advanced gastric cancer patients following DCS therapy

Background Although JCOG0405 revealed preoperative S-1 plus cisplatin chemotherapy followed by surgery was safety and effective, it was not clear for detailed consideration, such as the correlation between the number of metastatic lymph nodes and prognosis. In this study, we demonstrated the significance of para-aortic lymph node dissection (PAND) for advancedgastric cancer patients following DCS therapy. Methods Between July 2005 and November 2015, we evaluated retrospectively 24 advanced gastric cancer patients with para-aortic lymph node metastasis diagnosed by thin slice helical CT scan, without hematological metastasis or disseminated metastasis (16a2b1: 14, +a: 10). Patients received two or three cycles of preoperative chemotherapy consistingofdocetaxelandcisplatin(35mg/m2) onday1 and15andoralS-1 (40mg/m2 twice daily) on day 1-14 every 4weeks. After chemotherapy, gastrectomywith systematic PAND (16a2b1) was performed. The lymph nodes with disappeared cancer cellsduetochemotherapyweredeterminedasfollows:noevidenceofcancercellsbyH- E staining; lymphoid follicles were disturbed by fibrosis and granulomatous changes. Results Response rate was 92%, and pathological response rate was 77%. The adverse eventsrelatedDCStherapy(G3/4) were38%ofneutropenia,8%ofdiarrheaand8%of anorexia. Gastrectomywith PANDrequired396min(median) ofoperation timeand lost1225gofblood.Mediannumberofdissectedpara-aorticlymphnodewas13. Surgery related complications were anastomotic leakage in 2, chyle leakage in 2, and pancreas fistula in 1, postoperative bleeding in 1 and SSI in 1. The mean number of residual cancer cells in dissected para-aortic lymph node was 6, in which small lymph nodes without diagnosis as metastasis were contained. Three-years overall survival was 53%.Thepatientswith3morethanPANmetastasisorwithexpandlymphnode metastasis beyond 16a2b1 showed significantly worse prognosis than patients without them. Conclusions:AlthoughPANDfollowingDCStherapyhasunderwentsafely,this therapy should be only performed in specialized institutions. To improve prognosis, systematic PAND or basin dissection should be recommended rather than pick up dissection. Clinical trial indentification UMIN000006036 Legal entity responsible for the study N/A Funding N/A Disclosure All authors have declared no conflicts ofinterest.