Interpretation
Until now, studies highlighting the impact of learning curve on oncological outcomes in gynaecology mainly focused on conventional laparoscopy. A recent retrospective cohort study by Liu et al. showed that the adoption of conventional laparoscopy for the treatment of cervical cancer initially resulted in a significant reduction of DFS survival rates.32 In the years thereafter the survival rates in that study gradually improved up to the level before the adoption of conventional laparoscopy which strongly suggests an effect of a learning curve.32
Compared with conventional laparoscopy, the learning process of robot-assisted surgery was originally perceived as shorter. After the adoption of the robot-assisted approach, it was stated that the 3D view of robotic laparoscopy allows for a significantly better performance and faster improvement in learning curve than conventional laparoscopy with 2D view.33 Which specific part of robot-assisted radical hysterectomy (RRH) or robot-assisted PLND contributes to the learning curve the most, remains to be established. From their data on the different parts of robot-assisted surgery in endometrial cancer, Seamon et al. concluded that hysterectomies – and in particular the closure of the vaginal cuff – had the longest learning curve.34
Another recent study suggested an impact of the learning curve on oncological outcomes after robot-assisted surgery in cervical cancer patients.35 Chong et al. reported inferior OS after RRH during the learning period compared with conventional laparoscopic radical hysterectomy (LRH) performed by experienced surgeons, though not significant (P- value of 0.07).35 Given the small study size (n = 65) and the absence of a CUSUM analysis, the exact length of the learning curve could not be defined in that study.
With the use of RA-CUSUM analysis we approached the absolute number of procedures needed for a single surgical team to obtain robotic proficiency. More importantly, we were able to demonstrate the impact of the learning curve on the oncological outcomes of early stage cervical cancer patients. Our results underscore the necessity of a validated learning curriculum to make the learning process of an innovative surgical technique as effective and short as possible.20,33 Nowadays, simulation training should be mandatory and followed by robot-assisted procedures using dual consoles. This allows for direct supervision of new trainees by a certified proctor. Further research in larger populations and other centres is needed to be able to determine to what extent the length of the initial learning phase will be universally applicable.
Furthermore, we propose that the learning curve effect on oncological outcomes should be included in the design of future studies – including posthoc analyses of existing trials – comparing the safety of innovative and common surgical treatments.