Data on the oncologic adequacy and perioperative outcomes of robotic HCC resection is limited, particularly from the United States. Prior studies have not raised the issue of resection margin distance3,,,, which has become a topic of important debate in the era of minimally invasive liver surgery, since many surgical oncologists are still skeptical of the oncological outcomes after laparoscopic or robotic liver resection. Robotics, perhaps due to superior degrees of freedom over laparoscopy, can reduce the need for an unplanned conversion to an open approach, which can have an impact on OS. In addition to the current literature, which demonstrates acceptable short and long-term perioperative outcomes after robotic HCC resection6,,,,, data justifying the robot approach from a resection margin standpoint is required. The majority of published western reports only consist of small case series with < 50 patients16. To our knowledge, this study represents the largest single-center series of robotic liver resection for HCC in North America, contributing the most substantial data yet.
This study complements the nascent but growing research evaluating robotic approaches to HCC resection, especially in the western countries where HCC is far less common compared to Asia. Satisfactory perioperative outcomes, OS and resection margins were demonstrated via the robotic approach, suggesting this modality a promising strategy in HCC resection. Aforementioned oncologic concerns seem to be unfounded. Despite a lack of tactile feedback, even challenging posterosuperior lesions can be safely resected robotically while leading to low postoperative complications, decreased ICU utilization, and a short overall LOS.
HCC recurrence after hepatectomy significantly deteriorates long-term OS. The issue of HCC recurrence was explained by the cone unit concept, thus many experts favor anatomical liver resection3 since non-anatomical resection is associated with an increased recurrence,. HCC uniquely spreads intrahepatically via portal and hepatic venous tributaries, resulting in malignant thrombosis in advanced disease3. Margin widths greater than those demanded in other hepatic malignancies are required to reduce recurrence, particularly when anatomical resection is infeasible, , , . It is important to recognize that HCC can also manifest as a multicomponent or multifocal lesion whose peripheral microsatellite elements can involve resection margins. Lastly, the remnant cirrhotic parenchyma is also a fertile bed for de novo carcinogenesis, potentially confounding true recurrence.
The multitude of factors driving HCC carcinogenesis has contributed to a widely varying suggestion for an ideal margin, from 5-20mm,,,. Margin width importance rises with lymphovascular invasion, , microsatelliting tumors, and high PET-avidity. Conversely, narrower margins are acceptable for ‘early-onset’ lesions and those lacking microvascular invasion. Few studies have demonstrated findings to the contrary,, and those that do appear to suffer from data heterogeneity.
Our study demonstrated a statistically significant survival advantage in those who attained adequate margins beyond 1 mm with 88% OS up to 5 years. A large majority of our patients attained pathologic true negative margins; at least 81% had ≥ 1.1 mm margins, suggesting that the robotic platform leads to an oncologically adequate hepatectomy and excellent long-term OS.
Collectively, margin width plays a significant role and should be harvested proportional to the HCC biology, its vascular invasive patterns and hepatic segmental anatomy. With the robotic platform, adequate margin width can be attained as this study has demonstrated. We hope it and subsequent studies after it will enrich the current knowledge as we gain more experience and data with robotic HCC resections.
The limitations of this study include a relatively small sample size without randomization nor comparison with an open cohort. It is methodologically difficult to propensity match patients between robotic and open approaches due to the inherent difference in case complexity. At this time, we believe demonstrating the technical and oncologic feasibility of robotic HCC resection is a good first step toward multi-institutional randomized prospective trials. We were unable to obtain adequate data on DFS, due to the decentralized and variant nature of the electronic medical records used by our referring providers. However, this can be indirectly examined, since HCC recurrence presents the most common cause of cancer-specific mortality to patients after HCC resection. The superior OS associated with superior margin acquisition likely reflects a corresponding superior DFS.