Laparoscopic Ileocecal-Sparing Hemicolectomy for Cancer of Hepatic Flexure and Proximal Transverse Colon: A Single Arm Prospective Study.

e15650 Background: Traditional right hemicolectomy（TRH）is the standard operation for right colon cancer. The resection includes intestines from the terminal ileum to the middle of the transverse colon, as well as the ileocecum. The ileocecum is considered to have a “valve-like” function to reduce intestinal reflux and the incidence of diarrhea, which also play an important role in enterohepatic circulation and intestinal immunity. As for cancers in hepatic region and proximal transverse colon, is it possible to preserve ileocecum and ensure the oncological curative? Methods: We previously reported the procedure of laparoscopic ileocecal-sparing right hemicolectomy (LISH). The lymphatic adipose tissue around ileocolic artery and vein（ICA/ICV）,including 201d(lymph node around colic branch of ICA), 202, 203LN, was dissected. The colic branches of ICA/ICV were selectively ligated. The main trunk, cecal branches and ileal branches of ICA/ICV were preserved. The right colic artery/vein and middle colic artery/vein were ligated at roots，which was the same as TRH. End-to-end anastomosis between cecum and transverse colon was applied through an opening at the bottom of cecum. This was a single arm prospective study (NCT04479111) to evaluate the feasibility of LISH. Patients with hepatic flexure and proximal transverse colon cancer, aged 18-75, without distant metastasis were included. Primary endpoint was postoperative complications and 1-year local recurrence; secondary endpoints included rate of conversion to TRH, lymphadenectomy and complete mesocolic excision (CME) quality, surgical margin and 1-year disease-free survival (DFS) rate. Results: As of Jan.16th, 2022, 31 patients had been enrolled，including 9 patients with stage I, 9 patients with stage II and 13 patients with stage III. All enrolled patients received LISH successfully. The rate of high-quality lymphadenectomy (harvested LN > 12) was 96.8% and high-quality CME (Grade I/II) was 100%. All patients had negative resection margin and adequate proximal resection margin (median 9.1cm). 201d/202/203 lymph nodes were evaluated separately, and no metastatic 201d/202/203 LN were detected. Clavien-Dindo grade I adverse events within 90 days were occurred in 6 patients (19.4%), including wound infection(n = 2), anemia(n = 2), diarrhea(n = 1) and intestinal obstruction(n = 1). 1-year local recurrence rate is 0%, while 1-year DFS rate is 96.77%, only 1 stage III patient was diagnosed as ovarian metastases 9 months after radical operation. Conclusions: In this study, we provide a new radical operation choice for patients with hepatic flexure and proximal transverse colon cancer. LISH presented good perioperative safety，operation quality，and preliminary oncological safety within 1 year. We are launching a multicenter phase III study to verify the result and further explore the long-term oncological outcome. Clinical trial information: NCT04479111 .