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Labadie et al. Hepatoma Res 2020;6:65 I http://dx.doi.org/10.20517/2394-5079.2020.86 Page 3 of 6

The modern liver surgeon is afforded with numerous technical approaches to the resection of liver tumours.
Although several matched comparisons and meta-analyses have been performed examining the differences
between RALLR and several types of laparoscopic liver resection (LLR), many of these are limited by
[27]
retrospective design and confounded by selection biases . One of the largest studies comparing RALLR
and LLR matched 57 RALLR to 114 LLR based on background liver disease, extent of resection, diagnosis
[28]
and other patient demographic factors . The authors concluded that RALLR and LLR displayed similar
safety and feasibility for hepatectomies, but that more resections approached robotically were completed
totally minimally invasively compared to LLR, with a significant proportion of their LLR cohort requiring
hand-assist port. The clinical impact of hand-port utilization on postoperative pain and quality of life is
[29]
unclear. Magistri et al. compared RALLR and LLR specifically for HCC and reported similar outcomes
between both approaches.

A specific indication where RALLR may be advantageous to standard LLR is the resection of liver segments
in the posterosuperior segments (S1, S4A, S7, S8), which are difficult to approach by standard LLR.
Challenges in these approaches for standard LLR include poor visualization, difficulty in haemorrhage
control, as well as deep, curved or angled parenchymal transection planes associated with the posterior
location of these segments. Although tumourectomies and segmentectomies of these segments can
be feasibly approached laparoscopically, they often require expert skill and invasive manoeuvres (i.e.,
transpleural approach), potentially limiting their generalizability [30,31] . Laparoscopic right hepatectomy
is often the preferred approached to resections of these lesions since it is technically less challenging.
Several studies have evaluated RALLR for parenchymal-sparing resection of lesions in the posterosuperior
segments, with authors concluding that RALLR does indeed offer specific advantages to standard LLR and
may serve as an alternative to open resection for these lesions [32-36] . A review of our institutional series of
over 250 RALLR similarly corroborate these findings.

Enhanced efficacy of systemic therapies has provided significant benefit for patients with primary and
secondary hepatic malignancies and highlighted the importance of parenchymal sparing resections when
performing hepatectomy, as more patients may benefit from resection of intrahepatic recurrence. This
trend in management has challenged liver surgeons to totally extirpate tumours while preserving maximal
liver parenchyma, which is often damaged following numerous rounds of systemic chemotherapy, to allow
for future liver-directed therapies. Performing these resections from a minimally invasive approach may be
advantageous to survival by minimizing postoperative complications and potentially expediting a return
to adjuvant therapy, although additional confirmatory data are needed. Nevertheless, it is appealing to
speculate that performing minimally invasive parenchymal-sparing liver resections is advantageous for
certain liver cancer patients.

New technologies to improve pre-operative planning, intra-operative decision making, and surgical
[37]
training are being developed for the da Vinci robotic surgical system . Advances in image-guided liver
surgery, surgical resection maps, 3D modelling, and indocyanine green fluorescence with near-infrared
fluorescent imaging and 3D modelling have been developed to assist the surgeon and surgical trainee.
In collaboration with Intuitive, our group has helped to develop novel interactive 3D models for pre-
operative planning and intra-operative navigation [Figure 1]. Numerous three-dimensional virtual-reality
robotic surgery simulators now exist for surgical trainees to improve robotic technique and simulate real-
life operative situations. Furthermore, development of novel robotic surgical systems by companies such as
Medtronic, Johnson & Johnson, and TransEnterix will only propel ongoing technological innovation. We
hope these innovative new technologies translate into improved surgical outcomes for our patients and a
well-trained next generation of minimally invasive liver surgeons.

In conclusion, RALLR is a safe and effective approach to the minimally invasive resection of hepatic
malignancies. In experienced hands, it is equivalent to the standard laparoscopic approach to anterior