In this study, RA surgery, performed at a single center by the same surgeon, showed a shorter total operative time, less blood loss, and shorter hospital stay than those shown by open surgery. RA surgery also showed a shorter operative time and trend toward a reduced length of hospital stay than those shown by LA surgery. The frequency of complications was the lowest in RA surgery and did not differ between LA and open surgeries. No complications occurred with RA surgery, at least in patients aged > 61 years. These results suggest that RA surgery is less invasive and more effective than open or LA surgery in the treatment of early-stage endometrial cancer.
Reports on the advantages of RA surgery for endometrial cancer have increased in recent years. Regarding the learning curve, in one study, the operative time was shorter and complications were fewer in procedures using a robotic system than those in procedures not using it [8]. In our study, the total operative time significantly decreased as the surgical experiences increased. Prior studies comparing open and LA surgery with pelvic lymphadenectomy for endometrial cancer also indicated that the learning curve for RA surgery can be achieved after a few cases [9, 10]. In these studies, the learning curve was achieved after approximately 20 cases, similar to the finding in our study. Thus, our results are comparable to those reported previously, and the accuracy of our surgical outcomes is worthy of consideration.
Robot-assisted surgery is associated with early discharge because of the low frequency of postoperative pain. Naixin et al. investigated the safety of same-day discharge of patients who underwent RA surgery for endometrial cancer [11]. They reported that over 80% of the patients were discharged on the day of surgery with several criteria met, including oral intake, ambulation, and postoperative Hb levels (decrease of 2 g/dL or less from baseline), and only 1.3% of the patients visited the emergency department within 30 days after surgery. In our study, many patients were discharged on the fifth postoperative day, but discharge may have been possible on the third or fourth day. However, we believe that for early discharge, it is essential to have an environment in which patients can receive medical care if any symptoms appear, as well as sufficient discharge guidance. This point is important because medical insurance systems differ among countries.
In elderly patients, open surgery is associated with an approximately 2.5-fold higher perioperative complication rate than that associated with RA surgery [12]. Antonio et al. reported that the risk of perioperative complications with RA surgery for endometrial cancer decreases as the patient’s age increases. In the present study, perioperative complications were frequently observed among patients in the open surgery group, but none were observed even among patients aged over 61 years in the RA surgery group. Elderly patients often have comorbidities, with a high risk of requiring surgery and anesthesia. Therefore, MIS is increasingly being used in this patient population. In one study comparing LA and RA surgery for elderly patients with endometrial cancer, there was no difference in perioperative complications between the two groups [13]; however, in our study, perioperative complications were less frequently observed in the RA group than those in the LA surgery group. In RA surgery, the abdominal wall is lifted when the robotic arm is connected, allowing for a lower insufflation pressure than that allowed by LA surgery. Therefore, compared with LA surgery, RA surgery is useful not only for obese patients but also for elderly patients because its effect on cardiac output and respiratory motion owing to increased abdominal pressure can be reduced with it. In Japan, the aging society is expected to progress in the future, and the reduction in complications due to RA surgery is considered to be beneficial not only to patients but also to the medical economy.
There are several limitations to this study. First, the single-center setting of this study may have introduced a bias; further, the skills of the surgeon could also have influenced our results. However, our results are comparable to those reported previously; therefore, the data can be considered generalizable. Second, there is the variable follow-up between the three groups. This is inevitable given that the different surgical techniques were used at different time points. Third, the sample size was small. Since large-scale data analyses are needed in Japan, data of registration projects need to be analyzed by relevant academic societies.
RA surgery is now commonly performed overseas, and new surgical support equipment is being developed. As the demand and popularity of RA surgery increase, the demand for safe surgical methods will also increase [12]. In the present study, the efficacy and safety of RA surgery for endometrial cancer were investigated, and it was found that RA surgery was less invasive than open and LA surgeries. Currently, RA surgery for endometrial cancer is limited to patients with a low risk of recurrence. In the future, we expect the addition of patients with a high risk of recurrence to the group of eligible patients so that a high number of patients can receive minimally invasive treatment.