Systematic review analysis of robotic and transanal approaches in TME surgery- A systematic review of the current literature in regard to challenges in rectal cancer surgery.

Several patients' and pathological characteristics in rectal surgery can significantly complicate surgical loco regional tumor clearance. The main factors are obesity, short tumor distance from anal verge, bulky tumors, and narrow pelvis, which have been shown to be associated to poor surgical results in open and laparoscopic approaches. Minimally invasive surgery has the potential to reduce perioperative morbidity with equivalent short- and long-term oncological outcomes compared to conventional open approach. Achilles' heel of laparoscopic approaches is conversion to open surgery. High risk for conversion is evident for patients with bulky and low tumors as well as male gender and narrow pelvis. Hence, patient's characteristics represent challenges in rectal cancer surgery especially in minimally invasive approaches. The available surgical techniques increased remarkably with recently developed and implemented improvements of minimally invasive rectal cancer surgery. The controversial discussions about sense and purpose of these novel approaches are still ongoing in the literature. Herein, we evaluate, if latest technical advances like transanal approach or robotic assisted surgery have the potential to overcome known challenges and pitfalls in rectal cancer surgery in demanding surgical cases and highlight the role of current minimally invasive approaches in rectal cancer surgery.