When is enough enough?—predicting adequacy of portal vein embolization for hypertrophy of the future liver remnant in the age of liver venous deprivation

Introduction

Preservation of an adequate future liver remnant (FLR) is mandatory for safe hepatectomy. The most clinically relevant estimate of the FLR in Western patients is the standardized FLR (sFLR), which is the 3-dimensional liver volume calculated using triphasic computed tomography (CT) scans normalized to a patient’s body surface area (BSA) (1). An sFLR of at least 30% is associated with a 0% rate of death due to liver failure in patients undergoing resection of colorectal liver metastases after extensive preoperative chemotherapy (2). In addition, an sFLR under 30% is predictive of postoperative hepatic insufficiency (PHI) and death in patients undergoing resection of hilar cholangiocarcinoma (3).

Portal vein embolization (PVE) is a common procedure to induce growth of an initially insufficient FLR. Kinetic growth rate (KGR), calculated by dividing the change in sFLR by the elapsed time in weeks, is the factor most predictive of PHI and mortality in patients who undergo resection after PVE. In fact, the risk of liver-failure-related death is negligible in patients with KGR of at least 2% per week (4). Thus, in our practice, KGR of at least 2% per week or sFLR of at least 30% are well-established thresholds for safe hepatectomy after PVE.

In 2009, Hwang et al. introduced hepatic vein embolization (HVE) as a sequential salvage procedure for patients who do not have sufficient hypertrophy with PVE (5). Recently, in 2016, simultaneous HVE and PVE, together known as liver venous deprivation (LVD), was introduced by Guiu et al. to induce FLR hypertrophy when PVE alone is thought to be inadequate (6-9). Our group has used HVE both as a salvage procedure following insufficient sFLR hypertrophy after PVE and as part of upfront LVD in patients with particularly small sFLR (10,11). Several studies, including a recent meta-analysis, showed that LVD induces greater hypertrophy compared to PVE (6,9,12,13). The efficacy of LVD has led some to advocate for this procedure in all patients who require FLR hypertrophy. However, the addition of HVE to PVE carries additional procedural time, cost, and risk (14), and there are no established criteria to guide its use.

In this study, we sought to identify factors associated with insufficient FLR hypertrophy after right PVE or extended PVE alone. This helps identify patients who may require upfront alternative procedures, such as LVD, to achieve adequate hypertrophy. We further assess the additional procedural time and cost associated with LVD to help guide the judicious use of this procedure. We present this article in accordance with the STROBE reporting checklist (available at https://hbsn.amegroups.com/article/view/10.21037/hbsn-24-415/rc).

Methods

Patient selection and data collection

This was a single-center retrospective cohort study of consecutive patients who underwent right PVE with or without embolization of segment IV branches to induce FLR hypertrophy before hepatectomy for any indication during 1998–2020. Patients were excluded if they underwent LVD, underwent staged PVE, or had a missing liver volume (Figure 1). Clinicopathologic and demographic characteristics were collected from a departmental database and electronic medical records (Epic, Verona WI, USA). The study was conducted in accordance with the Declaration of Helsinki and its subsequent amendments. The Institutional Review Board at The University of Texas MD Anderson Cancer Center approved this study protocol (#2023-0433) and waived the requirement for informed consent.

Figure 1 Flow chart showing selection of analysis cohort. HVE, hepatic vein embolization; MDACC, The University of Texas MD Anderson Cancer Center; PVE, portal vein embolization.

Liver volumetry and PVE

Patients with oncologically resectable liver tumors underwent assessment of FLR volume from contrast-enhanced CT scans performed with a multidetector row CT scanner using a triphasic liver protocol at 2.5, 3, or 5 mm slice thickness. Liver volumes were determined after loading contrast-enhanced CT images onto an Advantage Workstation 4.1 (GE Medical Systems, GE HealthCare Technologies Inc., Chicago, IL, USA). sFLR was estimated using a previously described formula: sFLR = FLR volume (cm³)/total estimated liver volume (TELV) (cm³) (15), where TELV was calculated based on the patient’s BSA by the following formula: TELV = 1,267.28 × BSA (m²) – 794.41 (1). KGR was calculated as the change in sFLR divided by the number of weeks between PVE and post-PVE sFLR measurement (4,16).

The PVE procedure has been standardized at The University of Texas MD Anderson Cancer Center from 1998 until 2020 which includes all patients in the study (15,17,18). A transhepatic ipsilateral approach was used for PVE. A combination of calibrated microparticles or polyvinyl alcohol and coils were used to occlude portal vein branches (15,17,18). When an extended right hepatectomy was anticipated, segment IV portal vein branches were embolized (17,19). In patients with biliary obstruction, biliary drainage was done before PVE based on recommendations from previous studies (3).

Post-PVE sFLR assessment was performed within 2–8 weeks after PVE, during which the volume of the FLR is stable (16). Adequate liver regeneration was defined as post-PVE sFLR at least 30% or KGR at least 2% per week. Patients with adequate liver regeneration but progressive disease did not undergo resection. Some patients with insufficient liver growth but controlled disease had serial sFLR measurements to allow time for additional hypertrophy. In these patients, post-PVE sFLR was the sFLR calculated closest to the clinical decision related to resection. Decision to perform surgery was based on sFLR, KGR, disease status, and the surgeon’s clinical judgement.

Definitions

Extended PVE was defined as right PVE with embolization of segment IV branches. Pre-PVE systemic therapy was defined as systemic therapy delivered within 12 months before PVE. Pre-PVE body mass index (BMI) was BMI calculated during the pre-PVE assessment visit. Post-PVE BMI was BMI calculated on the day of post-PVE CT scan. Stable weight was defined as post-PVE body weight within 2.4% above or below pre-PVE body weight, as used by other authors investigating cancer-associated weight change (20). Weight gain and weight loss were defined as post-PVE body weight more than 2.4% higher or lower than pre-PVE body weight, respectively. History of liver disease was defined based on previous clinical assessment and serologic markers. Gross liver appearance was defined as surgeon interpretation of the non-embolized liver appearance at the time of surgery or diagnostic laparoscopy before PVE, which is prospectively recorded in our institutional database. The decision to include gross liver appearance rather than microscopic liver condition was based on the pragmatic consideration related to surgeons’ judgement for decision making based on the gross appearance of the liver remnant. Moreover, because we do not routinely obtain biopsies of the non-embolized liver, microscopic liver condition was not available for the majority of patients. PHI was defined as peak total bilirubin level at least 7 mg/dL (21,22). Postoperative mortality was defined as death within 90 days of hepatectomy.

Procedural time and cost analyses and post-procedural admission

Proponents of indiscriminate LVD argue that the end goal should be to achieve as high a sFLR as possible and point to the safety of this procedure. Yet, few have examined the implications of the two approaches related to duration, post-procedural admission, and cost. To evaluate these variables, contemporary cohorts of patients who underwent PVE or LVD within the past five years [2019–2024] were evaluated. All procedures analyzed for cost were conducted during the recent few fiscal years to avoid the confounding impact of inflation. All cost data were provided by the University of Texas MD Anderson Cancer Center financial/accounting departments. Total cost was calculated as the sum of both indirect and direct costs from admission through discharge. Procedure time and hospital admission data were extracted from the electronic medical record. As this manuscript was not intended to directly compare LVD to PVE, but rather sought to focus on predictors of adequacy of PVE, we intentionally omitted clinical outcomes of LVD so as not to distract from the key questions pursued.

Statistical analysis

Continuous variables were presented as median and interquartile range (IQR) and compared using Kruskal-Wallis test or Mann-Whitney U test. Categorical variables were compared using χ² test. Predictors of post-PVE sFLR at least 30% and KGR at least 2% per week were determined by binary logistic regression model analyses. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated for each factor on univariable analyses. Factors with P value less than 0.1 on univariable analysis and those deemed clinically important by the authors based on previous literature were advanced to multivariable analysis (23). Multivariable logistic regression was performed using the backward elimination method. P value less than 0.05 was considered statistically significant, and all tests were 2-sided. Receiver operating characteristic (ROC) curve analysis was used to determine the optimal cut-off for pre-PVE sFLR predictive of post-PVE sFLR. Statistical analysis was performed using SPSS version 24 (IBM, Aramark, NY, USA).

Results

Patient characteristics

The final cohort included 477 patients who underwent PVE. Median age was 58 years, and 322 patients (68%) were male (Table 1). Median pre-PVE and post-PVE BMI were 27.3 (IQR, 24.5–30.8) and 27.2 (IQR, 24.5–30.6) kg/m², respectively. Between the pre-PVE and post-PVE assessments, 258 patients (54%) had stable weight, 113 (24%) lost weight, and 106 (22%) gained weight. Most patients had no history of liver disease or diabetes. Of the 453 patients with assessment of gross liver appearance, the liver was considered normal in 337 (74%), fibrotic/cirrhotic in 38 (8%), and steatotic/consistent with chemotherapy-associated liver injury (CALI) in 78 (17%). The most common tumor diagnosis was colorectal liver metastases (n=317, 66%), followed by hepatocellular carcinoma (n=56, 12%).

Most patients received pre-PVE systemic therapy (n=364, 76%), and the median number of cycles received was 7 (IQR, 4–11) (Table 1). Among patients who received systemic therapy, 264 (73%) received oxaliplatin, 91 (25%) received irinotecan, and 278 (76%) received anti-vascular endothelial growth factor (VEGF) agent. Median pre-PVE sFLR in the whole cohort was 21.8% (IQR, 16.4–29.1%). Extended PVE was done in 268 (56%) patients. Post-PVE sFLR was assessed a median of 4.4 weeks (IQR, 3.7–5.5 weeks) after PVE. Median post-PVE sFLR was 32.7% (IQR, 25.8–40.4%) and median KGR was 2.2% per week (IQR, 1.4–3.2%).

Most patients (n=360, 75%) underwent surgery after PVE (Table 2). The reasons for not undergoing surgery (n=117) were insufficient hypertrophy in 23 (20%), abnormal liver appearance in 22 (19%), progressive malignancy in 55 (47%), and others in 17 (15%). Staged resection was planned for 169 patients (35%), of whom 118 (70%) underwent second-stage resection. The reasons for not undergoing surgery in patients planned for staged resection were insufficient hypertrophy in 15 (29%), abnormal liver appearance in 4 (7.8%), progressive malignancy in 23 (45%), and others in 9 (18%) patients. Of 360 patients who underwent surgery, 23 (6.4%) had PHI, and 8 (2.2%) died within 90 days of surgery.

Patient characteristics according to post-PVE sFLR and KGR

Among the 477 patients, 284 (60%) had a post-PVE sFLR of at least 30%. Patients who did and did not achieve post-PVE sFLR of at least 30% did not differ in age, sex, pre- or post-PVE BMI, rate of diabetes mellitus, known liver disease, tumor diagnosis, or the type and duration of pre-PVE systemic therapy (Table 1). However, patients with post-PVE sFLR of at least 30% had a lower rate of weight gain after PVE, higher rate of non-normal gross liver appearance, higher median pre-PVE sFLR, lower rate of extended PVE, and higher median KGR.

A total of 271 patients (57%) had a KGR of at least 2% per week. Patients who did and did not achieve a KGR of at least 2% per week did not differ in age, sex, pre- and post-PVE BMI, rate of diabetes mellitus, known liver disease, liver tumor diagnosis, or gross liver appearance (Table 1). However, patients who achieved a KGR of at least 2% per week had a lower rate of post-PVE weight gain (P=0.008), lower rate of pre-PVE systemic therapy use (P=0.03), and lower rate of extended PVE (52% vs. 62%, P=0.02). Median pre-PVE sFLR was similar in the two KGR groups, but median post-PVE sFLR was higher for patients with a KGR of at least 2% per week.

Surgery and outcomes according to post-PVE sFLR and KGR

Patients with post-PVE sFLR of at least 30% had a higher surgery rate, lower PHI rate, and lower 90-day mortality rate (Table 2). Similarly, patients with KGR of at least 2% per week had a higher surgery rate, lower PHI rate, and lower 90-day mortality rate. Similarly, patients who achieved either one of the two endpoints had a higher surgery rate, lower PHI rate and lower 90-day mortality rate (Table S1). The reasons for not undergoing surgery are detailed in Table 2 and Table S1.

Staged resection was planned in 169 patients (35%). The rate of 2-stage hepatectomy completion was higher in patients with a post-PVE sFLR of at least 30% than in those without and higher in patients with a KGR of at least 2% per week than in those without (Table 2). The reasons for not undergoing the second stage resection are detailed in Table 2.

Nine patients underwent salvage HVE after inadequate hypertrophy. These patients were analyzed based on sFLR and KGR measured after PVE prior to salvage procedures and considered to have failed to achieve adequate post-PVE hypertrophy, irrespective of their sFLR and KGR after salvage HVE (10).

Predictors of adequate post-PVE sFLR and/or KGR

On univariable analysis, weight gain and extended PVE were associated with not achieving a post-PVE sFLR of at least 30% while gross liver appearance of fibrosis/cirrhosis, gross liver appearance of steatosis/CALI, and higher pre-PVE sFLR were associated with achieving a post-PVE sFLR of at least 30% (Table S2). On multivariable analysis, extended PVE (OR, 0.47; P=0.02) was associated with lower odds for achieving sFLR ≥30% and higher pre-PVE sFLR was associated with higher odds for achieving post-PVE sFLR ≥30% (OR, 1.40; P<0.001). ROC curve analysis revealed that a pre-PVE sFLR cut-off of 19% was 89% sensitive and 75% specific and a pre-PVE sFLR cut-off of 26% was 55% sensitive and 97% specific for predicting a post-PVE sFLR of at least 30% (AUC =0.914; Figure 2A). While most patients (83%) with a pre-PVE sFLR of less than 19% did not achieve a post-PVE sFLR of at least 30%, nearly all patients (96%) with a pre-PVE sFLR greater than 26% achieved a post-PVE sFLR of at least 30%. Among patients with a pre-PVE sFLR of 19% to 26%, 69% achieved a post-PVE sFLR of at least 30%, while 31% did not (Figure 2B).

Figure 2 Relationship between pre-PVE sFLR and post-PVE sFLR. (A) Receiver operating characteristic curve to define the optimal cut-off for the pre-PVE sFLR predictive of post-PVE sFLR of ≥30%. AUC =0.914. (B) Numbers and proportions of patients achieving post-PVE sFLR of ≥30% based on pre-PVE sFLR of <19%, 19% to 26%, and >26%. AUC, area under the curve; PVE, portal vein embolization; sFLR, standardized future liver remnant.

Univariable analysis revealed multiple predictors of not achieving a KGR of at least 2% per week: weight gain, gross liver appearance of steatosis or CALI, receipt of pre-PVE systemic therapy, extended PVE and planned staged resection (Table 3). On multivariable analysis, weight gain (OR, 0.50; P=0.006), gross liver appearance of steatosis/CALI (OR, 0.56; P=0.03), extended PVE (OR, 0.60; P=0.02) and planned staged resection (OR, 0.41; P<0.001) remained significant.

Considering factors associated with a composite outcome of either sFLR greater than 30% or KGR greater than 2% per week, extended PVE (OR, 0.40; P=0.003), planned staged resection (OR, 0.42; P=0.001), and a pre-PVE sFLR (OR, 1.14; P<0.001) were associated with insufficient hypertrophy on multivariable analysis (Table 4). An sFLR cut-off of 19% was 72% sensitive for failure to achieve this composite endpoint on ROC analysis (Figure S1).

Procedure time and cost analysis and post-procedural admission

In this analysis portion of our study [2019–2024], 63 patients who received PVE were compared to 22 patients who received upfront LVD (Table 5). The median procedure time for LVD was significantly longer than that of PVE [247 (IQR, 198–292) vs. 169 (IQR, 137–212) minutes, P<0.001] and more patients were admitted for observation post-procedure for LVD compared to PVE (50% vs. 27%, P=0.048). The procedural costs were higher for LVD (P<0.001) and the average procedural cost for LVD was 1.22 times greater than that for PVE. The total costs were higher for LVD (P<0.001) and the average total cost for LVD was 1.44 times greater than that for PVE.

Discussion

PVE is a well-established, safe, and effective intervention to induce FLR hypertrophy. However, up to 30% of patients do not achieve adequate hypertrophy with PVE alone (24-26). In this study, we evaluated factors associated with insufficient FLR hypertrophy after right PVE in 477 patients, the largest cohort to date. We found that pre-PVE sFLR less than 19%, significant weight gain after PVE, extended PVE, and planned staged resection were predictive of insufficient hypertrophy with PVE alone. In this patient cohort, a strong argument could be made to consider upfront LVD to achieve adequate hypertrophy of the future liver remnant.

The pre-PVE sFLR is perhaps the most intuitive predictor of an adequate post-PVE sFLR. Our goal was to identify a specific threshold below which PVE is unlikely to be adequate for obtaining a final sFLR of at least 30%. ROC curve analysis revealed pre-PVE sFLR of 19% to be a highly sensitive threshold. Furthermore, nearly all patients with an sFLR above 26% obtained a post-PVE sFLR of at least 30%. Interestingly, gross liver fibrosis/cirrhosis and steatosis/CALI were associated with post-PVE sFLR of at least 30% on univariable analysis. This might be explained by a higher pre-PVE sFLR in these patients compared to patients with a grossly normal liver appearance (median 28.5% vs. 20.3%, P<0.001), reflecting an inherent selection bias. These patients presumably underwent PVE due to the surgeon’s concern about underlying liver dysfunction and a higher risk of PHI, using FLR hypertrophy and KGR in response to PVE as a physiologic test of functional liver reserve. Not surprisingly, when adjusted for pre-PVE sFLR, these factors no longer predicted adequate hypertrophy.

Unlike sFLR, which is a static estimation of liver volume, KGR is a dynamic reflection of the liver’s regenerative capacity. This study confirms prior findings that a KGR less than 2% per week is associated with increased risk of PHI and 90-day mortality (4). The association between weight gain and an inadequate KGR is mainly explained by the impact of BSA, a function of the patient’s height and weight, on the calculation of the sFLR. Because BSA lies in the denominator of the formula used to standardize the FLR, an increase in BSA with weight gain causes a decrease in sFLR. If post-PVE sFLR is lower due to weight gain, then DH (post-PVE sFLR − pre-PVE sFLR) and eventually KGR (DH ÷ number of weeks) will be lower as well (1,27). Moreover, weight gain and obesity may reflect poor health and nutrition (28). Indeed, 30% to 50% of obese patients are malnourished during preoperative laboratory evaluation (29,30). On the other hand, weight loss was not associated with an improved KGR despite having the opposite impact on BSA calculation. This finding might be explained by unintentional weight loss due to cancer-related cachexia in some patients, which would negatively impact FLR hypertrophy. In general, we encourage patients undergoing PVE to remain active and adhere to a high-protein diet to ensure healthy weight maintenance supporting liver hypertrophy. Future evaluation of healthy weight maintenance, programmed diet supplementation, and exercise in patients undergoing liver-regenerative interventions would help elucidate this relationship.

Staged resection is sometimes utilized in patients with bilobar colorectal metastases. In these patients, first-stage hepatectomy is performed to remove disease from the FLR (left liver or left lateral section) before PVE, which is followed by a right or extended right hepatectomy. It is suspected that the trauma incurred from the first-stage resection causes injury to the FLR and limits its ability to hypertrophy, leading to a lower KGR (31). Extended PVE was associated with lower odds of sFLR ≥30%, which can be explained by the fact that FLR for these patients consists of segments I, II and III only. Thus, they have a lower pre-PVE sFLR and consequently a lower post-PVE sFLR. Indeed, patients undergoing extended PVE in our cohort had a lower pre-PVE sFLR compared to those undergoing right PVE only (18.2% vs. 28.6%, P<0.001). Unexpectedly, extended PVE was also associated with lower odds of achieving KGR ≥2% per week. A previous analysis from our group showed that extended PVE was associated with increased hypertrophy of segments II–III compared to right PVE only. Importantly, we did not compare the KGR for the entire future liver remnant in that study (e.g., we omitted segment IV in the case of right PVE only, and segment I from both) (24). Upon further analysis of the current dataset (Table S3), patients who underwent extended PVE had higher segment I–III KGR (2.1% vs. 1.6% per week, P<0.001), consistent with our prior findings. However, patients with right PVE only had substantial segment IV hypertrophy that contributed to the significantly greater KGR of the entire FLR with right PVE only compared to extended PVE (2.5% vs. 2.1% per week, P<0.001; Table S3).

LVD has emerged as a minimally invasive means to augment FLR hypertrophy when PVE alone is insufficient, first having been introduced by Guiu and colleagues (8). Laurent et al. subsequently published a retrospective single-center experience comparing up-front LVD (n=32) to PVE (n=32) and found that LVD was associated with superior hypertrophy (61% vs. 29%, P<0.001), similar complication rates, and decreased risk of postoperative liver failure (0% vs. 23%, P=0.01) (6). These findings were also confirmed by the DRAGON collaborative analysis led by Heil et al. (9) Despite these promising results, there are no established guidelines for use of LVD. Also, the addition of HVE incurs additional procedural risk (14) and cost (i.e., procedure room time, supplies, and radiation exposure to the patient and operators). Indeed, our current study shows that LVD is associated with significantly longer procedure time, higher rates of hospital admission, and increased procedural and total costs that may be unnecessary for a large proportion of patients for whom PVE alone might have been sufficient.

These points should not be taken to mean that we oppose the use of LVD to achieve hypertrophy of the FLR when necessary. Instead, we argue that the use of LVD should be more discriminate and selective (after all, if the endpoint is to have as big a future liver remnant as possible in every case, why not subject every patient to LVD, regardless of their starting sFLR?), and the goal of the current study was to help define those selection criteria. Whereas we primarily used HVE as a salvage procedure after insufficient hypertrophy in response to PVE alone in our early experience (8), our use of upfront LVD has increased in recent years, primarily driven by the instinctive presumption that a small starting sFLR is unlikely to “get there”. This notion is supported by our current work. Interestingly, results from the DRAGON collaborative group in which Heil and colleagues demonstrated a more robust growth of the FLR with LVD than PVE further reinforce our findings: the median starting sFLR for patients in DRAGON was 18.0% for LVD patients and 18.5% for PVE patients (9). It would have been interesting to see the starting (pre-PVE) sFLR for the 68.1% of PVE patients in DRAGON who were able to undergo resection vs. the 31.9% who were not. We eagerly await the results of the DRAGON-2 trial (NCT05428735), HYPER-LIV01 trial, and future studies comparing the two techniques and strongly recommend that the investigators consider the starting sFLR as a potential stratification layer (32).

It is important to point out that a sFLR of 30% or a KGR of 2% per week are merely metrics meant to predict a 0% post-hepatectomy mortality (2-4,16). Surgeons may choose to proceed with surgery, as we ourselves have in this series, even when patients fail to meet these cutoffs based on a number of factors, including their judgement, patient wishes, and other uncaptured variables. Doing so unfortunately comes with a risk for higher postoperative complications and mortality, as borne out here as well. Therefore, we agree that every effort should be made to achieve an adequate FLR ahead of major hepatectomy. To this end, we propose a simple algorithm for use of PVE and LVD in patients requiring FLR hypertrophy (Figure 3). Patients with pre-PVE sFLR less than 19% should be considered for up-front LVD, while those with a starting sFLR greater than 26% can be expected to obtain adequate hypertrophy with PVE alone. Patients with pre-PVE sFLR of 19% to 26% and planned for either a staged hepatectomy or an extended right hepatectomy or have gross liver abnormalities should also be considered for LVD. If adequate hypertrophy is not obtained after PVE, HVE can still be used as a salvage procedure as previously reported (10). Other alternatives such as associating liver partition and portal vein ligation for staged hepatectomy (ALPPS) and its variations have also been described, but are not used in our practice (33-35). Weight gain after PVE was not included in this algorithm as it cannot be predicted before PVE or LVD but should be addressed as part of patient counseling. Moreover, significant weight gain should be considered by the surgeon when deciding to proceed with hepatectomy after FLR hypertrophy.

Figure 3 Algorithm for deciding between PVE and LVD on the basis of patient characteristics. Dashed lines indicate that a procedure should be considered. TELV is calculated based on the BSA according to the formula TELV =1,267.28 × BSA (m²) – 794.41 (1). *, based on findings from Hwang et al. (5) and Niekamp et al. (10) describing the use of salvage HVE after PVE. BSA, body surface area; HVE, hepatic vein embolization; LVD, liver venous deprivation; PVE, portal vein embolization; sFLR, standardized future liver remnant; TELV, total estimated liver volume.

Our findings should be interpreted with several limitations in mind. First, this represents a single-center retrospective study with a highly selected patient cohort. Validation in a multicenter cohort would improve the generalizability of these results. Nonetheless, this remains the largest cohort to date evaluating predictors of FLR hypertrophy. Second, most patients were treated for colorectal liver metastases; whether our findings are reliably generalizable to other histologies is unclear. Also, several patients undergoing PVE in our cohort had pre-PVE sFLR of at least 30% but underwent PVE for reasons not specified in the medical records, most likely the surgeon’s clinical impression of underlying liver dysfunction or lesion locations that might necessitate more extensive resections. Third, other centers may not use sFLR and KGR in their clinical decision making for assessment of FLR hypertrophy and resectability (36,37). Thus, the results of our study should be adapted accordingly to fit the practice for centers that use other measures for clinical decision making. Fourth, the results presented herein were obtained from our experience with PVE where particles and coils were the primary material used and may not be reflective of the effectiveness of other embolization material such as glue (38). Finally, PVE extended to segment IV is routinely performed at The University of Texas MD Anderson Cancer Center for patients planned for extended right hepatectomy. However, this is not universal practice, and centers that only perform right PVE should adapt the study results and perhaps lower the threshold for LVD to adjust for sFLR hypertrophy associated with segment IV embolization (39).

Conclusions

Patients with a baseline sFLR less than 19% and those with baseline sFLR 19–26% and gross liver abnormalities or requiring a staged or extended right hepatectomy are unlikely to achieve adequate hypertrophy with right PVE. LVD may be the preferred intervention for these patients as it is known to induce augmented hypertrophy. Conversely, patients with a baseline sFLR greater than 26% and those with baseline sFLR 19–26% and no risk factors are likely to achieve adequate hypertrophy with PVE to augment hypertrophy. Weight gain is associated with decreased chance of adequate hypertrophy, and healthy weight maintenance should be encouraged to optimize hypertrophy following PVE.

Acknowledgments

The authors thank Ms. Ruth Haynes for administrative support in the preparation of this manuscript and Ms. Stephanie Deming, Research Medical Library, MD Anderson Cancer Center, for copyediting the manuscript.

Footnote

Reporting Checklist: The authors have completed the STROBE reporting checklist. Available at https://hbsn.amegroups.com/article/view/10.21037/hbsn-24-415/rc

Data Sharing Statement: Available at https://hbsn.amegroups.com/article/view/10.21037/hbsn-24-415/dss

Peer Review File: Available at https://hbsn.amegroups.com/article/view/10.21037/hbsn-24-415/prf

Funding: The work was supported by the National Cancer Institute under award number P30CA016672, which supports the MD Anderson Cancer Center Clinical Trials Support Resource.

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://hbsn.amegroups.com/article/view/10.21037/hbsn-24-415/coif). The authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. The study was conducted in accordance with the Declaration of Helsinki and its subsequent amendments. The Institutional Review Board at The University of Texas MD Anderson Cancer Center approved this study protocol (#2023-0433) and waived the requirement for informed consent.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

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