The adoption of minimally invasive surgery in patients with RC has gained tremendous popularity due to its benefits, especially for low lying rectal cancers [26]. Results of the two major randomized trials demonstrated non-inferiority of laparoscopic RC surgery compared to the open approach [27, 28]. The ROLARR randomized clinical trial demonstrated no significant differences between the robotic and conventional laparoscopic TME in terms of conversion rates (adjusted OR = 0.61 [95% CI, 0.31 to 1.21]; p = 0.16). However, the multivariate analysis demonstrated that male (adjusted OR = 2.44 [95% CI, 1.05 to 5.71]; p = 0.04) and obese (adjusted OR = 4.69 [95% CI, 2.08 to 10.58]; p < 0.001) patients were prone to significantly higher conversion rates in the laparoscopic group [29]. Additionally, our recent study showed that obese and male patients with mid-low RC undergoing Lap-TME had a higher conversion rate and poorer specimen integrity and long-term local control compared to those undergoing Rob-TME [17]. The 10-year follow-up of 217 standardized Lap-TME cases performed by a single surgeon (O.A.) between 2005 and 2012, showed that oncological outcomes were adversely affected in open surgery converted patients [19]. In the conversion group (6.5%), DFS was 50.0%, whereas it was 78.3% in the laparoscopic group (p < 0.001). Chan et al. also reported higher rates of LR (9.8% vs. 2.8%; p < 0.001) and reduced cumulative DFS in colorectal cancer patients who had a conversion from laparoscopic to open procedures [30]. In contrast, compared to laparoscopy, robotic RC surgery provided lower conversion rates, better preservation of sexual function, and oncological outcomes [31, 32]. Also, the robotic approach has a shorter learning curve [33] and provides higher camera navigation quality than laparoscopy [34]. If the robotic approach could be theoretically advantageous for male patients with mid-low RC, for female patients both robotic and laparoscopic approach could provide similar results. The aim of the present study was to compare the laparoscopic approach in anatomically easier patients (females) with the robotic approach in anatomically challenging patients (males). Sex differences in pelvic anatomy and reflection on surgical outcomes as well as pathological metrics in RC surgery were widely described previously [35–38].
A female-wide pelvis is beneficial for the maneuverability of laparoscopic instruments during TME for RC. In contrast, it is challenging to perform Lap-TME in male patients with mid-low RC without damaging the mesorectal envelope and obtaining negative DRM and CRM. This was confirmed in our previous study, comparing Lap-TME (n = 84) and Rob-TME (n = 103) techniques in male patients with mid-low RC [17]. Rob-TME provides improved mesorectum specimen compared to Lap-TME (complete mesorectum, 93.2% vs. 44.1%) in male patients with mid-low RC. Additionally, we found differences in conversion rates in male patients with RC concerning laparoscopic and robotic approaches (Lap-TME 3.5% versus Rob-TME 0%) [17]. Also, Rob-TME decreases the local recurrence rate (LRR) and improves OS (LRR: 3.8% vs. 7.1%, OS: 87.0% vs. 85.7%) [17].
Multiple studies have been conducted on comparative analysis of laparoscopic and robotic approaches for RC surgery [17, 20, 29, 39, 40]. The effects of both techniques on perioperative (conversion to open surgery, amount of bleeding, operative time), postoperative (complication rates, length of postoperative hospital stay, pathological parameters), and oncologic outcomes (LRR, DFS, OS) were investigated. However, most of these studies included mixed-sex (male/female) patients. Due to the distinct difference in pelvic anatomy between male and female individuals, questions on superiority of laparoscopic or robotic approaches were made. The effects of these approaches on TME quality in both sex and its reflection on long-term oncological results have not been evaluated yet.
The adult male pelvis is more technically challenging during sphincter-preserving Lap-TME because of its anatomical features: narrow space, oval-shaped pelvic inlet, angle of the public arch less than 90 degrees, and the insertion level of the levator ani muscle which is lower [35]. Limited space restricts maneuverability of laparoscopic instruments, which translates into a decreased quality of mesorectal dissection, associated with higher conversion rate, and particularly impaired local control. Additionally, it becomes challenging to perform division of the rectum, requiring multiple number of staples in the depths of the pelvis which can increase the AL rates [41].
Pathological evaluation is essential for predicting the prognosis of patients after TME. Therefore, CRM, DRM, and mesorectal integrity are pathological metrics that play a crucial role in assessing TME quality and local control [4–6, 23]. Furthermore, the precise dissection provided through the robotic platform may be expected to improve the pathological metrics. Standardized TME procedures performed by experienced surgeons reduced the risk of obtaining CRM-positive specimens [19]. The high rate of CRM positivity reported in the Colorectal Cancer Laparoscopic or Open Resection (COLOR II) trial in the laparoscopic group has raised concerns regarding the feasibility of the laparoscopic approach for rectal cancer [27]. In the prospective study conducted by Baek et al., the CRM involvement was not statistically different between Lap-TME and Rob-TME groups [16].
A recent study showed that the rate of positive CRM was lower in the Rob-TME group than in the Lap-TME group [29]. Aliyev et al. found significant differences in CRM-positive rates between the Lap-TME (7.1%) and Rob-TME (3.0%) groups, including only male patients [17]. The authors concluded that Rob-TME allowed to achieve complete and oncological adequate resection of the specimen with lower CRM involvement than the Lap-TME in male patients [17].
On the contrary, the current study demonstrated that mesorectal integrity, CRM, and DRM results are similar if the TME is performed laparoscopically in females and robotically in male patients with mid-low rectal cancer. Moreover, long-term oncologic outcomes (OS, DFS, and LRR) are comparable in the two groups of patients. There was no conversion to open surgery in both groups of patients. Rob-TME in male patients provided more harvested lymph nodes than Lap-TME in female patients. M-Rob-TME was associated with a more extended operation time than the Lap-TME group. The postoperative complications rates were also comparable among the two groups of patients. Therefore, this study shows that performing Lap-TME in females is as good as Rob-TME in males on perioperative and oncological outcomes. This study could lead to a sex-based analysis between Lap-TME and Rob-TME on a wider scale in order to confirm these results. The possible outcome is to indicate Rob-TME especially to male patients, or generally complex pelvic anatomies, optimizing the implementation of the robotic platform for RC.
This study has several limitations. First of all, it was a retrospective analysis of prospectively collected data from a single surgeon's experience. Second, the number of Lap-TME procedures is lower than Rob-TME. A large prospective randomized study is needed to confirm our results. Third, side of the recurrences was not revealed in this study. Fourth, comparative functional outcomes (urinary, sexual, and overall quality of life) were not evaluated. Fifth, molecular and genetic data were unavailable in this study, and tumor behavioral biology may differ between the two sex, which may have affected the oncological outcomes. And finally, cost-effectiveness was not investigated in this study.