[A Case of Lower Rectal Cancer in Which Anal Preservation Was Achieved by Robotic Intra-Anal DST after Preoperative CRT and pCR Was Obtained].

A 40s woman visited her previous physician with a complaint of bloody stools, and a colonoscopy revealed lower rectal cancer. A close examination by our department revealed an advanced rectal cancer 1 cm to the dentate line, and a diagnosis of cT3N1M0, cStage Ⅲb was made. The circumferential resection margin(CRM)and distal margin(DM)were extremely close, making upfront surgery challenging in securing a surgical resection margin while also preserving the anus. This situation posed a high risk of local recurrence, leading to the decision for neoadjuvant therapy. After chemoradiation therapy (CRT), the patient showed a response of ycT3N0M0, ycStage Ⅱa and subsequently underwent robotic very low anterior resection. The anastomosis was performed using double stapling technique(DST)in the anal canal during robotic surgery. The pathology results revealed no residual tumor and no lymph node metastasis. We report a case in which a pathological complete response(pCR)was achieved after preoperative CRT, while successfully preserving the anus through intra-anal DST under robotic surgery.