Discussion
In this study, we divided patients into three groups according to the total volume of surgeons’ LRH experience, low-, mid- and high-volume groups, and analyzed their effects on surgical skills (operative time, blood loss) and patients’ long-term oncological outcomes (DFS, OS). We found that intraoperative blood loss decreased and operative time was significantly shortened with an increase in surgical volume, demonstrating that operative technology improves as surgeons gain more experience. This conclusion was consistent with that of most previous learning curve studies. Laparoscopic surgery involves new technologies and equipment, with the surgical field being transformed from traditional three-dimensional open surgery to two-dimensional laparoscopic surgery. The increase in surgical experience means repeated practice of surgical skills. In general, theoretical and practical research results confirm that laparoscopic surgery skills can be improved with an increase in surgical volume.
The LACC trial considered that the oncological outcomes of minimally invasive surgery for early cervical cancer were worse than those of traditional open surgery16,17. Many studies have explored the causes of the higher mortality and recurrence rate of LRH. In addition to the necessary technologies required for minimally invasive surgery, such as carbon dioxide pneumoperitoneum, uterine manipulators18-21 and other possible factors, the surgical experience of surgeons has also attracted more attention. However, there are few studies to date about laparoscopic surgery experience, and most are focused on the influence of surgical experience on surgical skills and perioperative outcomes, with little emphasis on oncological outcomes. This study explored the surgical volume of LRH and the long-term oncological outcomes of early cervical cancer patients based on the clinical diagnosis and treatment for cervical cancer in a mainland China (Four C) database (n=46313).
In a study of 4702 cases of prostate cancer patients involving 29 doctors, Vickers et al6 found 5-year recurrence rates of 17%, 16% and 9% for patients who underwent laparoscopic radical prostatectomy and whose surgeons had performed 10, 250 and 750 surgeries, respectively, suggesting that the 5-year recurrence rate of patients decreases with an increase in laparoscopic surgeon experience. In a recent multicenter study in Japan, Matsuo et al22defined low-volume hospitals as less than 32 cases of RH (radical hysterectomy) in 5 years, mid-volume hospitals as 32-104 cases, and high-volume hospitals as ≥ 105 cases. Based on analysis of the oncological outcomes of RH of 116 medical institutions, they considered that high-volume hospitals may be associated with the risk of local recurrence and the improvement of survival rate.
The results above are different from our findings. However, there are many differences in surgical difficulties and skills and the use of instruments between LRH and laparoscopic radical prostatectomy, such as the use of uterine manipulators in LRH. Nevertheless, previous results cannot be used to represent the impact of laparoscopic experience on the long-term prognosis of cervical cancer. For example, Matsuo et al22 overlooked the possible effect of the surgical approach on RH oncological outcomes. Moreover, the surgical volume of hospitals does not fully represent the surgical volume of surgeons, and there are also surgeons with poor surgical experience in high-volume hospitals and surgeons with rich surgical experience in low-volume hospitals; moreover, their grouping method of surgical volume, the minimum P-value method, might be flawed. They use this approach to identify the cutoff for surgical volume related to disease-free survival via an unadjusted Cox proportional hazard regression model. The first surgical volume exhibiting statistical significance is used to define low-volume centers, and the smallest P-value was defined for high-volume centers. This grouping led to differences in oncological outcomes between groups prior to analysis, making the differences controversial. Our study makes up for the deficiency of Matsuo et al. in not studying the experience of surgeons and unclear surgical approaches, and the grouping method of this study is not suspected of making analysis on the basis of known outcomes.
Chong et al23 analyzed the oncological outcomes of the first 50 LRH patients and the second 50 LRH patients of the same doctor and found that the long-term prognosis of the patients did not show significant improvement with the increase in surgical experience. However, it is undeniable that the operative time, hospital stay, time to restore normal residual urine volume, blood loss, intraoperative and postoperative complications are significantly reduced and that the number of lymph nodes acquired is increased with an increase in surgical experience. Based on analysis of the experience of a single surgeon in LRH, this study concludes that the increase in LRH experience may improve surgical skills but have no effect on oncological outcomes, which is consistent with our results. The previous study focused on the analysis of the results of the first 50 cases and the second 50 cases of a single doctor, with good consistency, but the sample size was small. In contrast, our study was a multicenter, multisurgeon, large-sample analysis, and Cox regression analysis and PSM were used to balance the case mix factors; thus, the results are more convincing.
However, we acknowledge several limitations in this study. First, this was a retrospective study with confounding factors. For example, in the high-volume group, the proportion of patients with LVSI and lymph node metastasis was higher than that in the mid- and low-volume groups. Nonetheless, we attempted to balance these differences through propensity score matching. Second, the case and report writing standards among hospitals might have been different, leading to the absence of clinical data. Third, although our study covered a total of 46,313 cases of cervical cancer inpatients in 37 hospitals in most of China, it did not cover all regions nationwide. Regardless, the database can comprehensively represent the diagnosis and treatment of cervical cancer in China. Fourth, because this database was a cervical cancer-specialized disease database, a small number of endometrial cancer patients who will also receive LRH may have been considered in this study, which might have affected the analysis of the effects of LRH surgical experience on surgical skills and oncology outcomes. Fifth, we only analyzed surgical skills and long-term oncological outcomes, without further exploration of the occurrence of near- and long-term complications. However, our team has conducted special discussions on complications, and we believe that a conclusion will be reached soon to compensate for the deficiencies in this study. Finally, there may be methodological flaws in defining the volume of surgery in this study. According to previous literature, we used 50 cases as the cutoff point to define low- and mid-surgical volumes and 100 cases as the cutoff point to define medium and high surgical volumes23-25, but others believe that LRH requires at least 23 cases to reach the proficiency level27. Although many studies on surgical experience take previous studies and experience as the basis of high and low surgical volumes, some studies have utilized the median method, the minimum p-value method, and the Jordan index methods to define the grouping of surgical volume22,27-28. The grouping method of surgical volume should be explored in future research.
Despite the above flaws, based on the large sample size of the study, we conclude the following clinical significance. First, we consider that surgical skills can be improved with rich experience. Shortening of the operative time and the reduction of intraoperative blood loss can minimize harm to patients during the operation. Second, surgical experience may not be the factor that affects long-term oncological outcomes of LRH. Therefore, we need to further explore the limitations of laparoscopic technology itself.
Conflicts of interest: All authors have no conflicts of interest to disclose.