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Tokunaga et al. J Cancer Metastasis Treat 2018;4:40 I http://dx.doi.org/10.20517/2394-4722.2017.80 Page 7 of 9

Short-term surgical outcomes such as intraoperative bleeding, surgical time, duration of postoperative
hospital stay, and postoperative morbidity and mortality rate are thought to reflect surgical quality, and
some of them directly affect patients’ quality of life. Therefore, these factors are frequently compared between
surgical procedures, when investigators need to show superiority or non-inferiority of a newly emergent
procedure. Indeed, they have been compared in many studies of RG and LG. However, it seems difficult to
conclude that RG is a superior procedure to LG in terms of short-term surgical outcomes, because RG is a
more time-consuming procedure, but does not show any obvious benefits. Although some have reported
that RG is associated with less bleeding, the differences, which were generally less than 100 mL, seem not
to be clinically meaningful. It might be difficult to demonstrate that RG could further improve short-term
surgical outcomes, because LG is already a well-established and satisfactorily safe procedure.

The number of studies focusing on long-term surgical outcomes is quite limited, due to insufficient follow-up
period in each study. So far, similar long-term survival outcomes between RG and LG have been reported,
and we need to wait for the results of currently ongoing studies to reach any conclusions about long-term
survival outcomes.

Interpretation of the results of comparative studies should be done carefully because of possible selection
bias. In most comparative studies, surgical approaches were selected by the patients themselves after
thoughtful explanation of both procedures, but the possibility of selection bias should be taken into account.
To overcome this issue, well designed prospective, hopefully randomized controlled, trials are necessary,
and we have to at least wait for the results of prospective non-randomized comparative studies .
[14]

To demonstrate the feasibility of RG, the surgical outcomes of RG are usually compared with those of LG.
However, considering that both surgeries were developed on the concept of being minimally invasive, the
differences between RG and LG might be marginal, even if RG is truly a superior procedure to LG. In
addition RG is, so far, obviously the more expensive surgical procedure. Therefore, it seems unrealistic for
RG to completely replace LG with all surgeries in the very near future. However, if the cost of RG decreases
dramatically and high medical expense is no longer a problem, it may be a different story with RG becoming
further widespread.

So far, RG seems to be as feasible as LG in terms of short- and long-term surgical outcomes. However, RG
is an expensive procedure at present, and it is unclear whether RG is superior to LG from the patients’
standpoint. The results of well designed prospective comparative studies are awaited to obtain conclusive
results on this issue.

DECLARATIONS
Authors’ contributions
Analysed and interpreted the data: Tokunaga M, Watanabe M, Sugita S, Tonouchi A, Kaito A, Kinoshita T
Read and approved the final manuscript: Tokunaga M, Watanabe M, Sugita S, Tonouchi A, Kaito A,
Kinoshita T

Availability of data and meterials
Not applicable.

Financial support and sponsorship
None.

Conflicts of interest
All authors declared that there are no conflicts of interest.