Minimally invasive surgery (MIS) has largely replaced open abdominal hysterectomy for early-stage endometrial cancer due to shorter recovery times, lower complication rates, and comparable oncological outcomes. Within MIS, two main approaches exist: conventional laparoscopy, where the surgeon directly manipulates instruments viewed through a camera, and robot-assisted MIS (RA-MIS), where the surgeon operates through a robotic interface that translates hand movements into precise instrument motion.
Robotic surgery has been adopted widely in gynecological oncology since the mid-2000s, driven by its purported advantages in precision, tremor filtering, and ergonomics for the surgeon. However, RA-MIS systems are substantially more expensive than conventional laparoscopy - both in equipment cost and per-procedure costs. Whether this additional expense translates into better patient outcomes has been debated, with most short-term studies showing comparable results.
Long-term oncological outcomes - specifically recurrence rates, survival, and cancer-specific mortality - are the most meaningful measures for a cancer operation. This retrospective study provides one of the more comprehensive comparisons of long-term outcomes between RA-MIS and laparoscopy for Stage I endometrial cancer, with a large cohort and extended follow-up.
The retrospective cohort included 1,027 Stage I endometrial cancer patients treated between 2006 and 2016: 461 laparoscopy and 566 RA-MIS. The time period spans the introduction and adoption of robotic surgery at the study institution, which allows for a natural comparison of two contemporaneous approaches rather than comparing against a historical control.
A major methodological challenge in comparing surgical approaches retrospectively is selection bias: surgeons and patients may systematically choose one approach over another based on tumor characteristics, patient factors, or institutional preferences, making naive comparisons unreliable. To address this, the authors used Inverse Probability of Treatment Weighting (IPTW), a statistical technique that reweights patients to create a pseudo-population in which RA-MIS and laparoscopy groups are balanced on measured confounders.
Three oncological outcomes were analyzed: recurrence-free survival (RFS), overall survival (OS), and disease-specific survival (DSS). Each was compared between groups using Cox proportional hazards regression after IPTW adjustment, with hazard ratios (HRs) quantifying the relative risk associated with RA-MIS versus laparoscopy.
After IPTW adjustment, RA-MIS was associated with significantly worse outcomes across all three endpoints. For recurrence-free survival: HR 1.41 (p=0.004); for overall survival: HR 1.39 (p=0.02); for disease-specific survival: HR 3.51. The disease-specific survival hazard ratio of 3.51 is particularly striking, suggesting that when patients do die from their cancer, those who had RA-MIS are substantially more likely to have had an earlier cancer-related death.
Median time to first recurrence was 16.3 months for RA-MIS versus 28.7 months for laparoscopy among patients who experienced recurrence - a difference of over a year. This suggests that recurrences after RA-MIS may occur earlier in the postoperative course, a pattern that could reflect differences in surgical quality or residual disease.
Follow-up times differed between groups: median follow-up was 8.7 years for laparoscopy patients and 6.3 years for RA-MIS patients, reflecting the more recent adoption of the robotic approach. While this limits the maturity of survival data for RA-MIS patients, the longer follow-up of laparoscopy patients actually works against finding worse outcomes in the robotic group (more time for the laparoscopy group to accrue events), making the observed associations more credible rather than less.
The authors and the broader surgical community have debated potential explanations for inferior oncological outcomes with robotic surgery. One hypothesis is uterine manipulator use: robotic surgery has historically required an intrauterine manipulator to position the uterus during surgery, and some evidence suggests manipulator use may increase the risk of positive peritoneal cytology and intraperitoneal tumor cell dissemination at the time of surgery.
A second hypothesis involves the learning curve effect. Robotic surgery was adopted at many institutions during the study period, meaning early robotic cases were performed by surgeons still mastering the technique. If robotic surgeons in the early adoption phase had higher rates of inadequate surgical margins, fewer lymph nodes removed, or longer operating times with greater blood loss, this could explain worse outcomes without reflecting the true potential of the approach as performed by experienced robotic surgeons.
It is also possible that the IPTW adjustment, despite being methodologically sound, did not fully control for all selection biases in this retrospective dataset. Unmeasured confounders - such as tumor molecular subtype, surgeon volume, or institutional protocols for lymph node assessment - could contribute to the observed differences. A randomized trial would be the only definitive way to separate technique effects from selection effects.
These findings raise important questions for gynecological oncology surgical programs that have invested heavily in robotic surgery platforms. The results do not necessarily mean robotic surgery should be abandoned - they may reflect historical practice patterns that have since been corrected - but they do suggest that ongoing prospective monitoring of oncological outcomes by surgical approach is essential.
Several modifications to robotic technique have been proposed and increasingly adopted in response to concerns like those raised by this study. Robotic surgery without uterine manipulator is now practiced at some centers and preliminary evidence suggests it may reduce peritoneal dissemination risk. If such modifications explain the inferior historical outcomes, contemporary RA-MIS cohorts might show different results than those reported here.
From a health economics perspective, the combination of higher cost and potentially worse oncological outcomes would make RA-MIS difficult to justify over conventional laparoscopy for straightforward Stage I endometrial cancer cases. However, RA-MIS may still offer advantages for specific patient subgroups - such as those with severe obesity where laparoscopic access is technically difficult - and should not be abandoned entirely based on retrospective data alone.
This study adds important long-term outcome data to a field where most comparative studies have focused on short-term perioperative measures. The large cohort size (1,027 patients) and use of IPTW statistical adjustment make it methodologically stronger than many prior comparisons, and the finding of worse oncological outcomes with RA-MIS across all three survival endpoints is a consistent, concerning signal.
The results align with some but not all prior studies in the literature. A few earlier studies also found worse outcomes with RA-MIS while others found no difference, and the mix of results reflects the challenge of comparing techniques across institutions with different adoption timelines, learning curves, and patient populations. Meta-analyses pooling data across studies show a more nuanced picture.
Ultimately, only adequately powered randomized controlled trials comparing contemporary laparoscopic and robotic techniques - ideally performed by experienced surgeons with high case volumes for both approaches - can definitively resolve whether the surgical approach itself affects endometrial cancer outcomes. Several such trials are underway or being planned, and their results will provide the definitive evidence base needed to guide future practice.