RObotic Versus LAparoscopic Resection for Rectal Cancer An International, Multicentre, Prospective, Randomised, Controlled, Unblinded, Parallel-group Trial of Robotic-assisted Versus Laparoscopic Surgery for Treatment of Rectal Cancer.

The feasibility and safety of laparoscopic surgery has been established for colon cancer. The case for rectal cancer is less clear, and of the reported multicentre trials only the Medical Research Council (MRC) CLASICC trial included an evaluation of laparoscopic compared to open rectal cancer surgery. Although both laparoscopic and open rectal cancer resection were associated with similar lymph node yields, concern was expressed at the higher rate of circumferential resection margin (CRM) involvement in the laparoscopic arm (12.4%) as compared to the open arm (6.3%) for patients undergoing anterior resection. This however did not translate into a difference in local recurrence at either 3-year or 5-year follow-up. The difference in CRM involvement was felt to reflect the increased technical difficulties associated with the laparoscopic technique in the rectal cancer subgroup. This was supported by the higher conversion rate in the laparoscopic rectal subgroup (34%) as compared to the laparoscopic colon subgroup (25%). Analysis of CLASICC data revealed higher morbidity and mortality rates associated with laparoscopic cases converted to open operation (30-day morbidity: laparoscopic 29%, converted 45%; in-hospital mortality: laparoscopic 1%, converted 9%). Some of this increased morbidity may be related to more advanced cancers requiring conversion, but a proportion will inevitably have resulted from the increased operative time, increased technical difficulty, and the need for a laparotomy wound in converted cases.

The introduction of robotic-assisted laparoscopic surgery using the da Vinci™ system (Intuitive Surgical, California, USA) promises to eliminate many of the technical difficulties inherent in laparoscopic surgery. It offers the advantages of intuitive manipulation of laparoscopic instruments with 7-degrees of freedom of movement, a 3-dimensional field of view, a stable camera platform with zoom magnification, dexterity enhancement, and an ergonomic operating environment. Experience has shown that the benefits of the robot are most appreciated when surgical accuracy is required within a confined space, such as the pelvis.

Laparoscopic rectal cancer surgery is technically demanding requiring accurate pelvic dissection according to total mesorectal excision (TME) principles with autonomic nerve preservation. Inadvertent injury to the nerves has been attributed to the higher rate of male sexual dysfunction following laparoscopic surgery. The practicalities of robotic-assisted colorectal cancer surgery have been reported in small series but only two studies have concentrated on rectal cancer, and only one of these performed a randomised comparison in a small number of patients.

The literature on robotic-assisted colon surgery is limited to 17 small case series. Most of these comprise mixed benign and malignant disease. The largest by D'Annibale et al reported 53 robotic-assisted colectomies and compared outcomes with 53 laparoscopic resections. It concluded that robotic-assisted surgery was as safe and effective as laparoscopic, was particularly useful in pelvic dissection, but that cost-effectiveness needed further evaluation. Other reports concur that robotic-assisted colorectal surgery is feasible and safe, with low rates of conversion, morbidity and mortality, but with increased operative times. There is only one study which has addressed the issue of hospital costs. This compared 30 robotic-assisted with 27 standard laparoscopic cases and concluded that the total hospital cost was higher for robotic surgery.

The feasibility of robotics for TME rectal cancer resection was established by Pigazzi et al in a series of 6 low rectal cancers. A subsequent follow-up study of 39 rectal cancers treated prospectively by robotic-assisted resection reported a zero rate of conversion with a mortality of 0% and morbidity of 12.8%. The only randomised trial compared 18 patients assigned to robotic-assisted resection with 18 patients assigned to standard laparoscopic resection. No difference was observed in the operative times, the conversion rates (2 laparoscopic, 0 robotic), or the quality of mesorectal resection. The only difference was the length of hospital stay, which was significantly shorter following robotic-assisted laparoscopic surgery (robotic-assisted: 6.9 +/-1.3 days; standard laparoscopic: 8.7 +/-1.3 days, p<0.001) and attributed to a reduction in surgical trauma by the authors. In addition to original reports, there has been one systematic review of robotic-assisted colorectal surgery, which concluded that "robotic colorectal surgery is a promising field and may provide a powerful additional tool for optimal management of more challenging pathology, including rectal cancer".