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.