Insufficient future liver remnant (FLR) represented one of the most common contraindications for major hepatectomy as post-hepatectomy liver failure (PHLF) was associated with high mortality with no effective treatment. Since the description of portal vein embolization (PVE) by Makucchi in 1984 (1), FLR volumetric modulation was made possible. Use of PVE before major hepatectomy for patients with insufficient FLR (i.e., <30% of estimated standard liver volume) had greatly improved resectability, operative as well as survival outcomes of patients with hepatocellular carcinoma (2). This has defined the role of PVE to be the standard approach for patients with insufficient FLR contemplating for major hepatectomy in the past decades. However, the need for 4 to 6 weeks waiting time to allow FLR hypertrophy undermined one of its major shortcomings. In a recent large series of PVE (3), 34% of the patients who initially had resectable disease was reported to become unresectable. Release of growth factors following embolization and the long waiting time after the procedure imposed a substantial risk of tumour progression, which accounted for the high unresectability rate after PVE. Furthermore, failed PVE and suboptimal FLR hypertrophy constituted another common reason for unresectability with up to 15% of the cases could not achieve adequate FLR hypertrophy after the procedure (2).
Since 2012, an alternative to PVE namely, associating liver partition and portal vein ligation for staged hepatectomy (ALPPS) started to become popular. The ALPPS approach was shown to be effective to induce substantial FLR hypertrophy in a much shorter period of time (22.7 vs. 3.8 cc per day) (4). In addition, rapid FLR hypertrophy was accompanied by the corresponding hepatic functional improvement (5). Parenchymal dissociation between FLR and the tumour bearing segment led to complete cut-off of the supply of intestinal trophic hormones to the liver lobe which is to be resected (6), and promote a dramatic volumetric and functional hypertrophy not achievable by PVE. Despite these advantages, ALPPS is often criticised for the increased procedure-related morbidity and mortality (6) in addition to the need for two-stage operation. Till quite recently, a procedure known as radiological simultaneous portohepatic vein embolization (RASPE) has been introduced, by inducing complete “venous deprivation” to induce FLR hypertrophy. Hepatic vein embolization (HVE) was initially developed as a sequential, supplementary procedure to salvage the suboptimal FLR hypertrophy from PVE (7). Considering its relatively low procedural risk (8), HVE and PVE are more frequently performed as a package (i.e., the RASPE) procedure in order to achieve maximal hypertrophy and avoid further delay with the sequential approach. Recently, a matched retrospective comparison between RASPE and PVE was published (9). Disregard the selection bias and small sample size in that study, it clearly demonstrated the superiority of RASPE over PVE alone in terms of the extent of anatomical, functional hypertrophy, compromising patient safety and short-term operative outcomes.
Although RASPE has emerged as an improved version of PVE that could one day become the standard approach for radiological FLR modulation, the impact of RASPE by simultaneously occluding the inflow and outflow vessels in the tumor-bearing liver lobes in diseased liver (i.e., cirrhotic liver, fatty liver, liver after chemotherapy, etc.) remained unclear. Besides, more data is required to define its long-term oncological outcomes in different cancer types. When compared with ALPPS which was FLR modulation by direct surgical means, there are pros and cons (Table 1) with RASPE in its own right. Clinicians should choose according to patient status (performance status), liver status (hepatic function and presence of parenchyma), tumour status (bilaterality and geometry) and availability of expertise. Future studies in a multi-centre prospective manner comparing RASPE and ALPPS would give us more valuable information about their respective roles in hepatectomy for insufficient FLR.
Provenance and Peer Review: This article was commissioned by the editorial office of Hepatobiliary Surgery and Nutrition. The article did not undergo external peer review.
Conflicts of Interest: Both authors have completed the ICMJE uniform disclosure form (available at http://dx.doi.org/10.21037/hbsn-20-862). Dr. ACYC serves as an unpaid editorial board member of HBSN. The other author has no conflicts of interest to declare.
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