Robotic vs. TaTME Rectal Surgery (ROTA STUDY) Matched Cohort Trial for Mid to Low Rectal Cancer Surgery Evaluation Trial in the Hands of an Experienced Surgeon

Introduction Colorectal cancer (CRC) is the fourth most common malignant disease with over 1 million new cases each year worldwide (1) The outcome of surgery for rectal cancer has improved substantially during the past two decades due to TME, which involves complete removal of the mesorectum with preservation of the pelvic autonomic nerves. Local recurrence rate of rectal cancer has fallen sharply because radially spread cancer cells in the mesorectum are removed by complete resection of this tissue.(2)(3)(4) Minimally invasive surgery (MIS) is slowly taking over as the preferred operative approach for colorectal diseases. Recently published randomized clinical trials (RCTs), such as COLOR II, COREAN and CLASICC, have shown better results for laparoscopic total mesorectal excision (in terms of short-term and long-term outcomes), when compared with open TME(5)(6)(7) However the utility of laparoscopic TME is limited in patients with low rectal cancer, who require surgeons with experience in ultra-low sphincter-saving laparoscopic surgery, which has a high risk of leaving a positive circumferential resection margin (CRM). In addition, narrow pelvic anatomy; male sex and high body mass index (BMI) are also unfavourable patient characteristics for a laparoscopic approach

The need to overcome these challenges has motivated surgeons to adopt alternative techniques. The two more recent procedures that have been introduced to surgical management of rectal cancer are robotic low anterior resection (RLAR) and Transanal Total Mesorectal Excision (TaTME). These two new procedures have the potential to overcome anatomical limitations like obesity, narrow male pelvis and bulky and low tumours to improve surgical treatment and thereby potentially oncological outcomes.

TaTME combines the TAMIS ( transanal minimally invasive surgery ) and trans-abdominal approaches in order to achieve TME.Transanal TME (TaTME) typically starts with the rectal resection and progresses to the splenic flexure/sigmoid colon mobilization in a "bottom-up" manner (8). A single-incision laparoscopic surgery port is introduced into the anal canal to gain endoscopic access to the rectum, pneumorectum is established, A purse-string suture is applied below the tumor, and this ensures an adequate oncological distal margin (9). Transanal excision is subsequently performed using laparoscopic instruments Rectal distension with CO2 combined with magnified optics permits excellent visualization of tissue planes. Easier access to the low rectum aid the surgeon with better quality TME and precise selection of the distal resection margin under direct visualization helps ensure an adequate margin. TaTME may potentially aid to a safer anastomosis by avoiding the multiple stapler firings often required in the laparoscopic approach and may result in higher rates of sphincter preserving surgery.

Robotic approach has been subject to much interest in recent years from its potential learning benefits to the operating surgeon and clinical benefits to the patients. Some of the clinical benefits include shorter hospital stay and improved functional outcomes compared to laparoscopic surgery (10) The other advantages provided by the robotic platform hold the potential to provide improved clinical outcomes, (11)(12) (13).

Both of the new procedures have been compared retrospectively to open and conventional laparoscopic surgery in various trials, which show that these methods are safe and feasible (9)(14). However, data on direct comparison of these two techniques are still lacking.