Preliminary report of tumor metastasis during liver regeneration after hepatic resection in rats

Protocol for the CoNoR Study: A prospective multi-step study of the potential added benefit of two novel assessment tools in colorectal liver metastases technical resectability decision-making

INTRODUCTION

Liver resection is the only curative treatment for colorectal liver metastases (CLM). Resectability decision-making is therefore a key determinant of outcomes. Wide variation has been demonstrated in resectability decision-making, despite the existence of criteria. This paper summarises a study protocol to evaluate the potential added value of two novel assessment tools in assessing CLM technical resectability: the Hepatica preoperative MR scan (MR-based volumetry, Couinaud segmentation, liver tissue characteristics and operative planning tool) and the LiMAx test (hepatic functional capacity).

METHODS AND ANALYSIS

This study uses a systematic multistep approach, whereby three preparatory workstreams aid the design of the final international case-based scenario survey:Workstream 1: systematic literature review of published resectability criteria.Workstream 2: international hepatopancreatobiliary (HPB) interviews.Workstream 3: international HPB questionnaire.Workstream 4: international HPB case-based scenario survey.The primary outcome measures are change in resectability decision-making and change in planned operative strategy, resulting from the novel test results. Secondary outcome measures are variability in CLM resectability decision-making and opinions on the role for novel tools.

ETHICS AND DISSEMINATION

The study protocol has been approved by a National Health Service Research Ethics Committee and registered with the Health Research Authority. Dissemination will be via international and national conferences. Manuscripts will be published.

REGISTRATION DETAILS

The CoNoR Study is registered with ClinicalTrials.gov (registration number NCT04270851). The systematic review is registered on the PROSPERO database (registration number CRD42019136748).

Transarterial Radioembolization to Impact Liver Volumetry: When and How

Inadequate volume of the future liver remnant (FLR) renders many patients with liver malignancies not amenable to surgical resection. Depending on the health of the liver and the patient in general, an FLR of 25-40% is required to avoid acute post-hepatectomy liver failure. Transarterial radioembolization (TARE) of a diseased liver lobe leads to atrophy of the embolized lobe and compensatory hypertrophy of the contralateral lobe. Although the absolute degree of FLR hypertrophy seems to be comparable to portal vein embolization, the kinetic of hypertrophy is much slower after radioembolization. However, TARE has the unique advantages of simultaneously offering local tumor control, possibly downstaging disease, and providing biological test of time. Progressions in technique and personalized dosimetry allow for more predictable ablative treatment of liver malignancies and preparation for major liver surgery. This article provides an overview of the existing literature, discusses the evidence, and considers possible criteria for patient selection.

Review of Use of Y90 as a Bridge to Liver Resection and Transplantation in Hepatocellular Carcinoma

BACKGROUND

The incidence of hepatocellular carcinoma (HCC) has been rising, and 80% of HCCs are unresectable at the time of presentation. In recent years, Yttrium-90 (Y90) radioembolization has arisen as a potential tool to treat the primary HCC tumor while also inducing contralateral liver hypertrophy to increase future liver remnant volumes. The goal of this multidisciplinary review is to summarize the contemporary evidence on the safety, efficacy, and utility of Y90 as a bridge to liver resection and transplant in patients with HCC.

METHODS

A narrative review was conducted of the recent literature regarding the utilization of Y90 as a therapy prior to liver resection or transplant in patients with HCC. A specific emphasis was placed on articles published in the last 10 years.

RESULTS

Y90 radioembolization has demonstrated a high safety profile and increasing utility in bridging and downstaging patients with HCC who subsequently undergo liver resection or transplant. The continuous advancements in treatment strategies and radiation dosimetry have paved the way for the incorporation of Y90 in all stages of HCC with different intents, including downstaging and bridging.

CONCLUSIONS

Y90 radioembolization can be safely used in the HCC population to bridge patients to resection or transplantation, induce future liver remnant growth, and select for less aggressive tumor biology prior to surgery.

Prospective study of change in liver function and fat in patients with colorectal liver metastases undergoing preoperative chemotherapy: protocol for the CLiFF Study

INTRODUCTION

Preoperative chemotherapy in patients undergoing resection for colorectal liver metastases (CLM) improves oncological outcomes. However, chemotherapy-associated liver injury (occurring in two patterns: vascular and fat deposition) is a real clinical concern prior to hepatic resection. After major liver resection, regeneration of the residual liver is a prerequisite for recovery and avoidance of liver failure, but this regenerative capacity may be hindered by chemotherapy. Thus, there is a need to predict for this serious complication. Over the past two decades, several tests and derived indices have been developed, which have failed to achieve clinical utility, mainly as they were indirect measurements of liver function. Here, we will use a novel test of liver function (the liver maximum capacity (LiMAx) test), and measure liver fat using MRI.

METHODS AND ANALYSIS

This prospective study will assess changes in liver function longitudinally, measured by the LiMAx test, and liver fat, measured by advanced MRI using both MR spectroscopy and the modified Dixon method, in up to 35 patients undergoing preoperative chemotherapy for CLM. The primary outcomes will be the changes in liver function and fat compared with baseline prechemotherapy measurements. Secondary outcome measures include: routinely measured liver function blood tests, anthropometric measurements, postoperative histology and digital quantification of fat, postoperative complications and mortality and quality of life.

ETHICS AND DISSEMINATION

The study was approved by a National Health Service Research Ethics Committee and registered with the Health Research Authority. Dissemination will be via international and national conferences and the National Institute for Health Research network. Manuscripts will be published.

TRIAL REGISTRATION NUMBER

This study is registered online at www.clinicaltrials.gov (registration number NCT03562234).

Hepatectomy increases metastatic graft and growth in an immunocompetent murine model of peritoneal metastases

BACKGROUND

Curative surgery of synchronous peritoneal metastases (PM) and colorectal liver metastases (LM) has been recently investigated as feasible option. When synchronous peritoneal and liver resection is not achievable, the sequence of the surgery remains unknown. Our hypothesis was that liver resection (LR) promotes peritoneal growth resulting in a non-resectable PM. We sought to analyse the effects of major LR and liver regeneration after hepatectomy in a murine model of PM and the associated angiogenesis.

METHODS

Murine model of colorectal PM in Balb/C mice was developed by intraperitoneal injection of different CT-26 tumour cell concentrations. Five days after the injection, mice were randomized into three groups: 68% hepatectomy group, sham laparotomy and control group without surgery. On post-operative days 1, 5 and 20, PM was evaluated macroscopically, tumour growth and liver regeneration by immunohistochemistry, and angiogenesis by immunofluorescence. Circulating progenitor cells, plasmatic cytokines and digestive arterial blood flow velocity measurements were also analysed.

RESULTS

Reproducible murine model of limited colorectal PM was obtained. Surgery induced PM increases and promoted neo-angiogenesis. Major hepatectomy influence the tumour growth in the late phase after surgery, the extent of extra-peritoneal metastasis and the increase of Ki-67 expression in the remnant liver.

CONCLUSIONS

This animal model confirms the pro-tumoural and pro-angiogenic role of surgery, laparotomy and major LR, which promotes the increase of angiogenic factors and their participation in PM growth. These results suggest that peritoneal resection should be first step in the case of two-step liver and peritoneal surgery for patients with colorectal PM and LM.

Multidisciplinary approach of colorectal cancer liver metastases

Large bowel cancer is a worldwide public health challenge. More than one third of patients present an advanced stage of disease at diagnosis and the liver is the most common site of metastases. Selection criteria for early diagnosis, chemotherapy and surgery have been recently expanded. The definition of resectability remains unclear. The presence of metastases is the most significant prognostic factor. For this reason the surgical resection of hepatic metastases is the leading treatment. The most appropriate resection approach remains to be defined. The two step and simultaneous resection processes of both primary and metastases have comparable survival long-term outcomes. The advent of targeted biological chemotherapeutic agents and the development of loco-regional therapies (chemoembolization, thermal ablation, arterial infusion chemotherapy) contribute to extend favorable results. Standardized evidence-based protocols are missing, hence optimal management of hepatic metastases should be single patient tailored and decided by a multidisciplinary team. This article reviews the outcomes of resection, systemic and loco-regional therapies of liver metastases originating from large bowel cancer.

Bilobar versus unilobar multiple colorectal liver metastases: a propensity score analysis of surgical outcomes and recurrence patterns

BACKGROUND

Bilobar multiple colorectal liver metastases (MCLM) are often considered incurable or associated with a poor prognosis even after R0 resection. This study was designed to compare the long-term outcomes and recurrence patterns after one-stage resection in patients with bilobar versus unilobar MCLM.

METHODS

The records of patients undergoing parenchymal-sparing intent hepatectomy between 1994 and 2015 were reviewed. Survival and recurrence patterns were analyzed by propensity score matching.

RESULTS

The study population included 140 patients: 81 patients with bilobar MCLM versus 59 patients with unilobar MCLM. In the propensity score matching analysis (bilobar, n = 35 vs. unilobar, n = 35), the short-term outcomes did not differ between the two groups. Five-year overall survival (54.8% in bilobar vs. 51.2% in unilobar; P = 0.388) and recurrence-free survival (28.5% in bilobar vs. 36.2% in unilobar; P = 0.261) also did not differ. No significant differences were found in liver-only recurrence (22.9% in bilobar vs. 25.7% in unilobar; P = 1.000) and other recurrence patterns.

CONCLUSIONS

The clearance of bilobar MCLM by one-stage resection of parenchymal-sparing intent provided comparable long-term survival to unilobar MCLM.

Multisciplinary management of patients with liver metastasis from colorectal cancer

Colorectal cancer (CRC) is one of the leading causes of cancer-related death. Surgery, radiotherapy and chemotherapy have been till now the main therapeutic strategies for disease control and improvement of the overall survival. Twenty-five per cent (25%) of CRC patients have clinically detectable liver metastases at the initial diagnosis and approximately 50% develop liver metastases during their disease course. Twenty-thirty per cent (20%-30%) are CRC patients with metastases confined to the liver. Some years ago various studies showed a curative potential for liver metastases resection. For this reason some authors proposed the conversion of unresectable liver metastases to resectable to achieve cure. Since those results were published, a lot of regimens have been studied for resectability potential. Better results could be obtained by the combination of chemotherapy with targeted drugs, such as anti-VEGF and anti-EGFR monoclonal antibodies. However an accurate selection for patients to treat with these regimens and to operate for liver metastases is mandatory to reduce the risk of complications. A multidisciplinary team approach represents the best way for a proper patient management. The team needs to include surgeons, oncologists, diagnostic and interventional radiologists with expertise in hepatobiliary disease, molecular pathologists, and clinical nurse specialists. This review summarizes the most important findings on surgery and systemic treatment of CRC-related liver metastases.

Parenchymal-sparing hepatectomy for deep-placed colorectal liver metastases

BACKGROUND

The feasibility of parenchymal-sparing hepatectomy has yet to be assessed based on the tumor location, which affects the choice of treatment in patients with colorectal liver metastases.

METHODS

Sixty-three patients underwent first curative hepatectomy for deep-placed colorectal liver metastases whose center was located >30 mm from the liver surface. Operative outcomes were compared among patients who underwent parenchymal-sparing hepatectomy or major hepatectomy (≥3 segments).

RESULTS

Parenchymal-sparing hepatectomy and major hepatectomy were performed for deep-placed colorectal liver metastases in 40 (63%) and 23 (37%) patients, respectively. Resection time was longer in the parenchymal-sparing hepatectomy than in the major hepatectomy group (57 vs 39 minutes) (P = .02) and cut-surface area was wider (120 vs 86 cm²) (P < .01). Resected volume was smaller in the parenchymal-sparing hepatectomy than in the major hepatectomy group (251 vs 560 g) (P < .01). No differences were found between the 2 groups for total operation time (306 vs 328 minutes), amount of blood loss (516 vs 400 mL), rate of major complications (10% vs 13%), and positive operative margins (5% vs 4%). Overall, recurrence-free, and liver recurrence-free survivals did not differ between the 2 groups. Direct major hepatectomy without portal venous embolization could not have been performed in 40% of the parenchymal-sparing hepatectomy group (16/40) because of the small liver remnant volume.

CONCLUSION

Parenchymal-sparing hepatectomy for deep-placed colorectal liver metastases was performed safely without compromising oncologic radicality. Parenchymal-sparing hepatectomy can increase the number of patients eligible for an operation by halving the resection volume and by increasing the chance of direct operative treatment in patients with ill-located colorectal liver metastases.

Parenchymal-Sparing Hepatectomy Does Not Increase Intrahepatic Recurrence in Patients with Advanced Colorectal Liver Metastases

BACKGROUND

Prophylactic impact of major hepatectomy (MH) on liver recurrence has yet to be clarified in patients with advanced colorectal liver metastases (CLMs).

METHODS

In our institute, parenchymal-sparing hepatectomy (PSH) is a standard procedure for CLMs consistently throughout initial and repeat resection, and MH is selected only in cases in which CLMs are close to major Glisson's pedicles. We reviewed 145 patients who underwent curative hepatectomy for advanced CLMs (≥4 nodules and ≤50 mm in size) from 1999 to 2012. Surgical outcomes and survival were compared between patients who underwent PSH and MH.

RESULTS

PSH was performed in 113 patients (77.9 %) and MH in 32 (22.1 %) patients with advanced CLMs. Tumor characteristics and short-term outcomes did not differ between the 2 groups. Incidence of positive tumor margin (8.8 % in PSH vs 9.4 % in MH; p = .927) and rates of liver-only recurrence (43.4 % in PSH and 50.0 % in MH; p = .505) did not differ. No significant differences were found in 5-year overall survival (37.0 % in PSH vs 29.4 % in MH, p = .473), recurrence-free survival (7.6 vs 6.8 %, p = .597), and liver recurrence-free survival (21.0 vs 21.3 %, p = .691). A total of 65 patients had liver-only recurrence, for which repeat hepatectomy was performed in 81.5 % (53 of 65) following our parenchymal-sparing approach.

CONCLUSIONS

In patients with advanced CLM, PSH does not increase positive surgical margin or liver recurrence in comparison with MH. A parenchymal-sparing approach offers a high rate of repeat resection for liver recurrence (salvageability).

Parenchymal-sparing Hepatectomy in Colorectal Liver Metastasis Improves Salvageability and Survival

OBJECTIVE

To investigate prognostic impact of parenchymal-sparing hepatectomy (PSH) for solitary small colorectal liver metastasis (CLM).

BACKGROUND

It is unclear whether PSH confers an oncologic benefit through increased salvageability or is a detriment through increasing recurrence rate.

METHODS

Database of 300 CLM patients with a solitary tumor (≤ 30 mm in size) was reviewed from 1993 to 2013. A total of 156 patients underwent PSH and 144 patients underwent right hepatectomy, left hepatectomy, or left lateral sectionectomy (non-PSH group).

RESULTS

The rate of PSH increased over the study period (P < 0.01). PSH did not impact negatively on overall (OS), recurrence-free, and liver-only recurrence-free survival, compared with non-PSH (P = 0.53, P = 0.97, and P = 0.69, respectively). Liver-only recurrence was observed in 22 patients (14%) in the PSH and 25 (17%) in the non-PSH group (P = 0.44). Repeat hepatectomy was more frequently performed in the PSH group (68% vs 24%, P < 0.01). Subanalysis of patients with liver-only recurrence revealed better 5-year overall survival from initial hepatectomy and from liver recurrence in the PSH than in the non-PSH group [72.4% vs 47.2% (P = 0.047) and 73.6% vs 30.1% (P = 0.018), respectively]. Multivariate analysis revealed that non-PSH was a risk of noncandidacy for repeat hepatectomy (hazard ratio: 8.18, confidence interval: 1.89-45.7, P < 0.01).

CONCLUSIONS

PSH did not increase recurrence in the liver remnant but more importantly improved 5-year survival in case of recurrence (salvageability). PSH should be the standard approach to CLM to allow for salvage surgery in case of liver recurrence.

A systematic review of contralateral liver lobe hypertrophy after unilobar selective internal radiation therapy with Y90

BACKGROUND

Curative liver resection is the treatment of choice for both primary and secondary liver malignancies. However, an inadequate future liver remnant (FLR) frequently precludes successful surgery. Portal vein embolization is the gold-standard modality for inducing hypertrophy of the FLR. In recent times, unilobar Yttrium-90 selective internal radiation therapy (SIRT) has been reported to induce hypertrophy of the contralateral, untreated liver lobe. The aim of this study is to review the current literature reporting on contralateral liver hypertrophy induced by unilobar SIRT.

METHODS

A systematic review of the English-language literature between 2000 and 2014 was performed using the search terms "Yttrium 90" OR "selective internal radiation therapy" OR "radioembolization" AND "hypertrophy".

RESULTS

Seven studies, reporting on 312 patients, were included. Two hundred and eighty four patients (91.0%) received treatment to the right lobe. Two hundred and fifteen patients had hepatocellular carcinoma (HCC), 12 had intrahepatic cholangiocarcinoma, and 85 had liver metastases from mixed primaries. Y90 SIRT resulted in contralateral liver hypertrophy which ranged from 26 to 47% at 44 days-9 months. All studies were retrospective in nature, and heterogeneous, with substantial variations relative to pathology treated, underlying liver disease, dosage and delivery of Y90, number of treatment sessions and time to measurement of hypertrophy.

CONCLUSION

Unilobar Y90 SIRT results in significant hypertrophy of the contralateral liver lobe. The rate of hypertrophy seems to be slower than that achieved by other methods.

A systematic review of contralateral liver lobe hypertrophy after unilobar selective internal radiation therapy with Y90

BACKGROUND

A curative liver resection is the treatment of choice for both primary and secondary liver malignancies. However, an inadequate future liver remnant (FLR) frequently precludes successful surgery. Portal vein embolization is the gold-standard modality for inducing hypertrophy of the FLR. In recent times, unilobar Yttrium-90 selective internal radiation therapy (SIRT) has been reported to induce hypertrophy of the contralateral, untreated liver lobe. The aim of this study was to review the current literature reporting on contralateral liver hypertrophy induced by unilobar SIRT.

METHODS

A systematic review of the English-language literature between 2000 and 2014 was performed using the search terms 'Yttrium 90' OR 'selective internal radiation therapy' OR 'radioembolization' AND 'hypertrophy'.

RESULTS

Seven studies, reporting on 312 patients, were included. Two hundred and eighty-four patients (91.0%) received treatment to the right lobe. Two hundred and fifteen patients had hepatocellular carcinoma (HCC), 12 had intrahepatic cholangiocarcinoma and 85 had liver metastases from mixed primaries. Y90 SIRT resulted in contralateral liver hypertrophy that ranged from 26% to 47% at 44 days to 9 months. All studies were retrospective in nature, and heterogeneous, with substantial variations relative to pathology treated, underlying liver disease, dosage and delivery of Y90, the number of treatment sessions and time to measurement of hypertrophy.

CONCLUSION

Unilobar Y90 SIRT results in significant hypertrophy of the contralateral liver lobe. The rate of hypertrophy seems to be slower than that achieved by other methods.

Contra-lateral liver lobe hypertrophy after unilobar Y90 radioembolization: An alternative to portal vein embolization?

Liver resection (LR) with negative margins confers survival advantage in many patients with hepatic malignancies. However, an adequate future liver remnant (FLR) is imperative for safe LR. Presently, in patients with an inadequate FLR; the 2 most established clinical techniques performed to induce liver hypertrophy are portal vein embolization (PVE) and portal vein ligation. More recently, it has been observed that patients who undergo treatment via Y90 radioembolization experience hypertrophy of the contra-lateral untreated liver lobe. Based on these observations, several investigators have proposed the potential use of this modality as an alternative technique for increasing the FLR prior to liver resection. Y90 radioembolization induces hypertrophy at a slower rate than PVE but has the added advantage of concomitant local disease control and tumour down-staging.

The role of hepatic ischemia-reperfusion injury and liver parenchymal quality on cancer recurrence

Hepatic ischemia/reperfusion (I/R) injury is a common clinical challenge. Despite accumulating evidence regarding its mechanisms and potential therapeutic approaches, hepatic I/R is still a leading cause of organ dysfunction, morbidity, and resource utilization, especially in those patients with underlying parenchymal abnormalities. In the oncological setting, there are growing concerns regarding the deleterious impact of I/R injury on the risk of post-surgical tumor recurrence. This review aims at giving the last updates regarding the role of hepatic I/R and liver parenchymal quality injury in the setting of oncological liver surgery, using a "bench-to-bedside" approach. Relevant medical literature was identified by searching PubMed and hand scanning of the reference lists of articles considered for inclusion. Numerous preclinical models have depicted the impact of I/R injury and hepatic parenchymal quality (steatosis, age) on increased cancer growth in the injured liver. Putative pathophysiological mechanisms linking I/R injury and liver cancer recurrence include an increased implantation of circulating cancer cells in the ischemic liver and the upregulation of proliferation and angiogenic factors following the ischemic insult. Although limited, there is growing clinical evidence that I/R injury and liver quality are associated with the risk of post-surgical cancer recurrence. In conclusion, on top of its harmful early impact on organ function, I/R injury is linked to increased tumor growth. Therapeutic strategies tackling I/R injury could not only improve post-surgical organ function, but also allow a reduction in the risk of cancer recurrence.

Underlying liver disease influences volumetric changes in the spared hemiliver after selective internal radiation therapy with 90Y in patients with hepatocellular carcinoma

OBJECTIVE

Hypertrophy of the contralateral liver lobe after treatment with yttrium-90 ((90)Y) microspheres has recently been reported. This study aimed to quantify left hepatic lobe hypertrophy after right-sided radioembolization for hepatocellular carcinoma (HCC) and to identify pretreatment predictive factors of hypertrophy in an Asian population.

METHODS

A retrospective review of patients with inoperable HCC undergoing selective internal radiation treatment (SIRT) with (90)Y microspheres at a single institution from January 2008 to January 2012 was performed. Only patients who had treatment delivered via the right hepatic artery alone were included.

RESULTS

In all, 17 patients fulfilling the study criteria were identified. The mean percentage of left-lobe hypertrophy was 34.2% ± 34.9% (range 19.0-106.5%) during a median of 5-month follow-up. Patients with hepatitis B were found to experience a significantly greater degree of hypertrophy than those with hepatitis C or alcoholic liver cirrhosis. There were no cases of acute liver failure after the administration of SIRT in this study and none of the patients developed disease in the contralateral lobe over the study period.

CONCLUSIONS

Administration of unilobar SIRT to the right liver lobe in patients with HCC resulted in a significant degree of contralateral left lobe hypertrophy. Patients with hepatitis B experienced a greater degree of hypertrophy than those with hepatitis C or alcoholic liver cirrhosis.

Different roles of hepatic hypothermic ischemia and ischemic preconditioning in chemically induced hepatocarcinogenesis in rats

BACKGROUND

Hepatic ischemia-reperfusion (IR) injury, an unfavorable complication of hepatectomy, could be prevented by hypothermic ischemia and ischemic preconditioning (IPC). However, the effects of these two approaches on hepatocarcinogenesis have not been examined. The aim of the study was to investigate roles of hypothermic ischemia and IPC in a chemically induced rat liver tumor model.

METHODS

Twenty-four Sprague-Dawley rats were treated with diethylnitrosamine and phenobarbital to induce hepatocellular carcinoma. Rats underwent hepatic ischemic injury, hypothermic ischemia, and IPC. Twenty-eight-wk-old rats were sacrificed to evaluate the morbidity and growth of liver tumor. Cytokines were measured at the protein and messenger RNA level.

RESULTS

IR injury significantly promoted liver tumor development. Intriguingly, hypothermic ischemia, but not IPC, delayed liver carcinogenesis, although both of them suppressed the hepatic IR injury. IPC-treated rats showed elevated interleukin (IL)-6 concentration in the serum and messenger RNA expression in liver. In addition, higher levels of IL-6 activated signal transducer and activator of transcription 3 in the liver of IPC-treated rats. The hepatic expression of target genes of signal transducer and activator of transcription 3 signaling, cyclin D1, c-myc, c-fos, and c-jun, all of which might participate in tumor progression, increased in IPC group, compared with that of IR group.

CONCLUSIONS

These data indicated hypothermic ischemia could ameliorate both IR injury and liver tumor development. However, IPC, another effective method to prevent hepatic IR injury, might exacerbate liver tumor growth. The elevated level of IL-6 was one of the reasons for the different effects of hypothermic ischemia and IPC on hepatocarcinogenesis in rats.

Tumour progression and liver regeneration--insights from animal models

Surgery remains the only curative treatment for colorectal liver metastases. For patients with multiple bilobar spread, extended hepatectomy might be required to achieve complete margin-free resection. In such cases, portal vein occlusion has been developed to induce preoperative hypertrophy of the future remnant liver and increase the resectability rate. Evidence now suggests that liver regeneration after hepatectomy and portal vein occlusion has a protumorigenic role, either through an upregulation of growth factors and cytokines or by haemodynamic changes in the blood supply to the liver. Experimental studies have reported a stimulatory effect of liver regeneration on the tumoral volume of liver metastases and on the metastatic potential of cells engrafted in the liver; this effect seems to depend on the timing of hepatectomy and portal vein occlusion. However, the variability of animal tumour models that are used for research in experimental colorectal liver metastases might account for some of the inconsistent and conflicting results. This Review presents clinical and experimental data pertaining to whether liver regeneration causes proliferation of tumour cells. We also analyse the different animal models of colorectal liver metastases in use and discuss current controversies in the field.

Increased growth of colorectal liver metastasis following partial hepatectomy

Nearly 50 % of colorectal cancer (CRC) patients develop liver metastases with liver resection being the only option to cure patients. Residual micrometastases or circulating tumor cells are considered a cause of tumor relapse. This work investigates the influence of partial hepatectomy (PH) on the growth and molecular composition of CRC liver metastasis in a syngeneic rat model. One million CC531 colorectal tumor cells were implanted via the portal vein in WAG/Rij rats followed by a 30 % PH a day later. Control groups either received tumor cells followed by a sham-operation or were injected with a buffer solution followed by PH. Animals were examined with magnetic resonance imaging (MRI) and liver tissues were processed for immunolabeling and PCR analysis. One-third PH was associated with an almost threefold increase in relative tumor mass (MRI volumetry: 2.8-fold and transcript levels of CD44: 2.3-fold). Expression of molecular markers for invasiveness and aggressiveness (CD49f, CXCR4, Axin2 and c-met) was increased following PH, however with no significant differences when referring to the relative expression levels (relating to tumor mass). Liver metastases demonstrated a significantly higher proliferation rate (Ki67) 2 weeks following PH and cell divisions also increased in the surrounding liver tissue. Following PH, the stimulated growth of metastases clearly exceeded the compensation in liver volume with long-lasting proliferative effects. However, the distinct tumor composition was not influenced by liver regeneration. Future investigations should focus on the inhibition of cell cycle (i.e. systemic therapy strategies, irradiation) to hinder liver regeneration and therefore restrain tumor growth.

Major liver resection stimulates stromal recruitment and metastasis compared with repeated minor resection

BACKGROUND

The present study examined the effects of types of liver resection on the growth of liver and lung metastases.

METHODS

Experimental liver metastases were established by spleen injection of the Colon 26 murine adenocarcinoma cell line expressing green fluorescent protein (GFP) into transgenic nude mice expressing red fluorescent protein. Experimental lung metastases were established by tail-vein injection with Colon 26-GFP. Three days after cell injection, groups of mice underwent (35% + 35% repeated minor resection versus 70% major resection versus 35% minor resection). Metastatic tumor growth was measured by color-coded fluorescence imaging of the GFP-expressing cancer cells and red fluorescent protein-expressing stroma.

RESULTS

Although major and repeated minor resection removed the same total volume of liver parenchyma, the 2 procedures had very different effects on metastatic tumor growth. Major resection stimulated liver and lung metastatic growth and recruitment of host-derived stroma compared with repeated minor resection. Repeated minor resection did not stimulate metastasis or stromal recruitment. No significant difference was found in liver regeneration between the 2 groups. Host-derived stroma density, which was stimulated by major resection compared with repeated minor resection, might stimulate growth in the liver-metastatic tumor. Transforming growth factor-β is also preferentially stimulated by major resection and might play a role in stromal and metastasis stimulation.

CONCLUSIONS

The results of the present study indicate that when liver resection is necessary, repeated minor liver resection will be superior to major liver resection, because major resection, unlike repeated minor resection, stimulates metastasis. This should be taken into consideration in clinical situations that require liver resection.

Effect of the pringle maneuver on tumor recurrence of hepatocellular carcinoma after curative resection (EPTRH): a randomized, prospective, controlled multicenter trial

BACKGROUND

Hepatic resection is currently still the best choice of therapeutic strategies for liver cancer, but the long-term survival rate after surgery is unsatisfactory. Most patients develop intra- and/or extrahepatic recurrence. The reasons for this high recurrence rate are not entirely clear. Recent studies have indicated that ischemia-reperfusion injury to the liver may be a significant factor promoting tumor recurrence and metastasis in animal models. If this is also true in humans, the effects of the Pringle maneuver, which has been widely used in hepatectomy for the past century, should be examined. To date, there are no reported data or randomized controlled studies examining the relationship between use of the Pringle maneuver and local tumor recurrence. We hypothesize that the long-term prognosis of patients with liver cancer could be worsened by use of the Pringle maneuver due to an increase in the rate of tumor recurrence in the liver remnant. We designed a multicenter, prospective, randomized surgical trial to test this hypothesis.

METHODS

At least 498 eligible patients from five participating centers will be enrolled and randomized into either the Pringle group or the non-Pringle group in a ratio of 1:1 using a permuted-blocks randomization protocol. After the completion of surgical intervention, patients will be included in a 3-year follow-up program.

DISCUSSION

This multicenter surgical trial will examine whether the Pringle maneuver has a negative effect on the long-term outcome of hepatocellular carcinoma patients. The trial will also provide information about prognostic differences, safety, advantages and disadvantages between Pringle and non-Pringle surgical procedures. Ultimately, the results will increase the available information about the effects of ischemia-reperfusion injury on tumor recurrence, which will be of immense benefit to general surgery.

TRIAL REGISTRATION

http://www.clinicaltrials.gov NCT00725335.

Liver resection for advanced or aggressive colorectal cancer metastases in the era of effective chemotherapy: a review

Liver surgery has been known to cure metastatic colorectal cancer in a small proportion of patients. However, advances in procedural technique and chemotherapy now allow more patients to have safe, potentially curative surgery. Here we review surgery for unresectable colorectal liver metastases using an expert multidisciplinary approach. With multidisciplinary management of patients with effective chemotherapy that can downstage metastases, more patients with previously inoperable disease can benefit from surgery. Portal vein embolization results in hypertrophy of the future liver remnant; on occasions, combining embolization with staged liver resection permits potentially curative surgery for patients previously unable to survive resection. However, increasing use of chemotherapy has raised awareness of potential hepatotoxicity and other deleterious effects of cytotoxic agents. Prolonged prehepatectomy chemotherapy therefore can reduce resectability even using a 2-stage procedure. Suitable timing of surgery for unresectable liver metastases during chemotherapy is critical. Because of advances in chemotherapy, colorectal cancer, like ovarian cancer, can now show survival benefit from maximum surgical debulking. Benefit from such maximum hepatic debulking surgery for metastatic colorectal disease is uncertain, but likely. Surgery in isolation may be approaching technical limits, but is now likely to help more patients because of the success of complementary strategies, particularly newer chemotherapy and targeted therapy. Expert individualized multidisciplinary treatment planning and problem-solving is essential.

The Pringle manoeuvre should be avoided in hepatectomy for cancer patients due to its side effects on tumor recurrence and worse prognosis

Curative hepatectomy is still the best therapeutic strategy for liver cancer treatment up to now. The Pringle manoeuvre has been commonly used to avoid massive blood loss during operation since its advent, which greatly accelerates the advance of liver surgery and oncological surgery. In the past century, more attentions have been paid to different effects of ischemia-reperfusion injury elicited by Pringle manoeuvre. Theses include its impacts on complex metabolic, immunological, and microvascular changes, which altogether might contribute to hepatocellular damage and dysfunction, and contribute to haemodynamic instability. Despite these adverse impacts, the short-term outcome of affected patients under hepatectomy was greatly improved with the advances of surgical techniques and perioperative management in recent years. While the long-term prognosis remains unsatisfactory due to a high incidence of intra/extrahepatic recurrence. The reason for it was not totally elucidated. Furthermore, the effect of the Pringle manoeuvre on the prognosis of oncologic patients and behavior of the tumor cell was not deliberately mentioned. This point was put forward to the front-desk by the specific phenomenon from recent animal studies. It is showed that ischemia-reperfusion injury of the liver remnant may be a significant factor to promote the tumor recurrence and metastasis. If it is a truth in human, there must be a big challenge to the Pringle manoeuvre. So we hypothesized that the long-term prognosis of cancer patients could be worsened by the ischemia-reperfusion injury elicited by Pringle manoeuvre during the hepatectomy and it should be revised, or even, avoided in future hepatectomy for oncologic patients. The less surgical stress including ischemia-reperfusion injury in the hepatic resection without Pringle manoeuvre might contribute to a better prognosis. To get a deeper understanding, prospective randomized clinical trials need to be done. It is surely supposed to provide more important information about the long-term effects of the Pringle manoeuvre, and to our hypothesis.

Impact of the degree of liver resection on survival for patients with multiple liver metastases from colorectal cancer

BACKGROUND

Although the degree of hepatic resection has been found to be a key aspect of tumor stimulation, the differences in clinical outcome between a massive liver resection and a less extensive resection for multiple colorectal metastases have not been well studied. The purpose of this study was to clarify the impact of the extent of liver resection on survival outcome.

METHODS

Clinicopathologic data were available for 85 patients who were surgically treated for four or more liver metastases. Forty-nine patients who underwent a major hepatic resection were compared with patients who underwent minor hepatic resections (n = 36).

RESULTS

As the patients undergoing major resection were more likely to have multiple (p = 0.014) and large tumors (p = 0.021) compared to the minor-resection patients, their overall survival was worse (p = 0.046) and the disease-free rate tended to be poorer. By multivariate analysis of the cohorts, the only independent factor affecting survival was the number of liver tumors (< or =5 or > or =6; relative risk [RR] = 0.427; p = 0.014). When patients with six or more metastases were selected and analyzed, the overall survival of patients who had a major resection was significantly poorer than those who had minor resections (p = 0.028), although the clinical characteristics were comparable between the two groups.

CONCLUSION

Although the extent of hepatectomy was not an independent prognosticator, minor resections for multiple colorectal metastases may offer a long-term survival advantage compared to a major resection.

Liver regeneration and tumor stimulation--a review of cytokine and angiogenic factors

Liver resection for metastatic (colorectal carcinoma) tumors is often followed by a significant incidence of tumor recurrence. Cellular and molecular changes resulting from hepatectomy and the subsequent liver regeneration process may influence the kinetics of tumor growth and contribute to recurrence. Clinical and experimental evidence suggests that factors involved in liver regeneration may also stimulate the growth of occult tumors and the reactivation of dormant micrometastases. An understanding of the underlying changes may enable alternative strategies to minimize tumor recurrence and improve patient survival after hepatectomy.

Ischemia-reperfusion of small liver remnant promotes liver tumor growth and metastases--activation of cell invasion and migration pathways

Elucidating the mechanism of liver tumor growth and metastasis after hepatic ischemia-reperfusion (I/R) injury of a small liver remnant will lay the foundation for the development of therapeutic strategies to target small liver remnant injury, and will reduce the likelihood of tumor recurrence after major hepatectomy or liver transplantation for liver cancer patients. In the current study, we aimed to investigate the effect of hepatic I/R injury of a small liver remnant on liver tumor development and metastases, and to explore the precise molecular mechanisms. A rat liver tumor model that underwent partial hepatic I/R injury with or without major hepatectomy was investigated. Liver tumor growth and metastases were compared among the groups with different surgical stress. An orthotopic liver tumor nude mice model was used to further confirm the invasiveness of the tumor cells from the above rat liver tumor model. Significant tumor growth and intrahepatic metastasis (5 of 6 vs. 0 of 6, P=0.015), and lung metastasis (5 of 6 vs. 0 of 6, P=0.015) were found in rats undergoing I/R and major hepatectomy compared with the control group, and was accompanied by upregulation of mRNA levels for Cdc42, ROCK (Rho kinase), and vascular endothelial growth factor, as well as activation of hepatic stellate cells. Most of the nude mice implanted with liver tumor from rats under I/R injury and major hepatectomy developed intrahepatic and lung metastases. In conclusion, hepatic I/R injury of a small liver remnant exacerbated liver tumor growth and metastasis by marked activation of cell adhesion, invasion, and angiogenesis pathways.

Liver regeneration stimulates tumor metastases

BACKGROUND

Partial hepatectomy for patients with colorectal liver metastases is associated with a tumor recurrence rate approaching 80% post-resection. Different factors and phases associated with regeneration of the liver are implicated in tumor recurrence. This study investigates the effects of the early and late phases of liver regeneration and the impact of the degree of liver resection on stimulating tumor growth and metastasis.

MATERIALS AND METHODS

Groups of mice underwent partial hepatectomy (37% or 70%) and were then challenged with colorectal liver carcinoma (CRC) tumors immediately after liver resection (early and late phase effect) or 6 days post liver resection (late phase effect). Tumor growth, degree of proliferation, tumor morphology, and the presence of extrahepatic metastases were investigated 21 days post-tumor induction.

RESULTS

The late phase of liver regeneration plays a significant role in tumor stimulation and metastasis. The degree of hepatectomy also appears to be an important factor. The degree of hepatic resection significantly influences tumor growth and the extent of extrahepatic metastases, particularly in the lungs.

CONCLUSIONS

Elucidation of the processes involved in the late phase of liver regeneration may assist in the development and timing of adjuvant agents to minimize tumor recurrence during this phase.

Altered growth patterns of colorectal liver metastases after thermal ablation

BACKGROUND

Thermal ablation by radiofrequency or laser is used increasingly for the treatment of colorectal liver metastases. Recurrence after thermal ablation is common and occurs both locally and at distant sites. One possible cause of this recurrence may be a result of growth stimulation of micrometastases in the remaining liver. This study examined the impact of thermal ablation on growth patterns of hepatic micrometastases.

METHODS

Colorectal liver metastases were induced in male CBA-strain mice via an intrasplenic injection of a murine-derived cancer cell line. Subtotal thermal ablation of the left posterior lobe of the liver (30% of total liver volume) was performed by neodymium yttrium-aluminum-garnet laser 7 days after induction of metastases. The distribution, number, cross-sectional diameter, volume, and proliferation rate of established neoplasms were compared with controls at 21 days after tumor induction. The effect of thermal ablation of 7% of the total liver volume by laser on the expression of vascular endothelial growth factor (VEGF), basic fibroblast growth factor 2 (FGF-2), transforming growth factor beta, and cellular proliferation (Ki-67 antigen) adjacent to the ablated site was assessed by immunohistochemistry in separate groups of animals at specific time points after therapy.

RESULTS

Thermal ablation did not alter the overall volume, number, size, and proliferation rate of neoplasms 21 days after laser ablation. There were no extrahepatic metastases after therapy. The number of neoplasms in the regenerated posterior lobe was equivalent to control despite subtotal ablation (29 +/- 2 vs 27 +/- 2; P = NS). A greater amount of metastases occupied the regenerated thermal-ablated lobe compared with controls (55% +/- 4% vs 29% +/- 3%; P < .04). Thermal ablation stimulated liver proliferation adjacent to the treatment site at 12 hours compared with untreated controls. Stimulation peaked at 72 hours (20% +/- 1% vs 1% +/- 1%; P < .001) and persisted to 21 days after therapy. FGF-2 and VEGF expression increased in liver tissue adjacent to the ablation site compared with baseline, peaking at 12 hours (112% +/- 2% vs 102% +/- 1%; P < .001) and 72 hours (114% +/- 2% vs 101% +/- 1%; P < .001), respectively.

CONCLUSIONS

Thermal ablation promotes the progression of micrometastases to form macroscopically detectable neoplasms in treated regenerating liver. This effect may relate to an increased expression of VEGF and FGF-2 adjacent to the treatment site.

Interstitial laser hyperthermia and the biological characteristics of tumor: study in a murine model of colorectal liver metastases

BACKGROUND DATA

Percutaneously applied interstitial laser hyperthermia (ILH) is a minimally invasive therapy that is currently used in the treatment of liver metastases. Despite its documented efficacy, theoretical considerations and evidence based on animal studies suggest the potential for stimulating tumor growth, especially following surgery. This study investigates the influence of ILH on tumor behaviour in an animal model of colorectal liver metastases.

MATERIALS AND METHODS

A model of colorectal cancer liver metastases in male inbred CBA mice was used. Laser hyperthermia was applied to tumor tissue using a bare optical quartz from a Medilas fibertom 4100 Nd:YAG surgical laser generator. Liver injury by ILH was initially produced in three experimental groups of animals at different time points in the development of metastases. ILH was applied (i) to normal liver 10 days prior to tumor induction, (ii) immediately prior to tumor induction, and (iii) 15 days after tumor induction to achieve approximately 8% liver destruction. Animals were killed 21 days after tumor induction, and the effects of ILH on overall tumor development were compared with controls using stereological assessment of tumor volume and by histology. In a separate experimental group, the effects of ILH on fully established tumors were examined. Suitable tumors were selected 21 days after induction and partially destroyed by ILH at a standard energy setting. Animals were then killed 15 days later, and the growth rate of the residual viable tumors was compared to control tumors having undergone sham procedures.

RESULTS

No significant stimulation of tumor growth was evident in any of the experimental groups following ILH, irrespective of the time of application. Incomplete tumor destruction also had no influence on subsequent tumor growth.

CONCLUSION

ILH does not influence the biological characteristics of tumors during any stage of the metastatic process.

Circulating tumor cell mRNAs in peripheral blood from hepatocellular carcinoma patients under radiotherapy, surgical resection or chemotherapy: a quantitative evaluation

We assessed whether current therapies could lead to hematogenous dissemination of malignant hepatocytes in hepatocellular carcinoma (HCC) patients using semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR) for alpha-fetoprotein (afp) and albumin (alb) mRNAs. We analyzed 137 peripheral blood samples before, during and after treatment from 84 patients under radiotherapy, surgical resection or chemotherapy. As compared to the upper limit for 53 healthy/non-HCC controls, alb- mRNA levels increased 2-10-fold in 6% of patients pre-treatment and 2-2.6x10(4)-fold in 32% post-treatment. Levels of afp- mRNA increased 3-210-fold in 17% pre-treatment and 4-5x10(5)-fold in 30% post-treatment. During a longitudinal follow-up of eight patients under radiotherapy or radiotherapy/resection, alb-mRNA levels were normal before treatment, whereas afp-mRNA levels increased 10-fold in two patients. During treatment, alb-mRNA and afp-mRNA levels increased 2-61-fold in three patients and 2.5-5-fold in two patients, respectively. After treatment, alb-mRNA levels declined to normal in all three patients within 3.5 months, but afp-mRNA levels increased 127-5x10(5)-fold in three patients within 5 months. We show evidence that HCC cells disseminating mostly post-treatment may be the 'seed' of recurrence/metastasis. In conjunction with the serum alpha-fetoprotein test, sequential afp-mRNA quantification could predict clinical metastasis/recurrence in 56% of patients during a 4-year follow-up.

Serum response of hepatocyte growth factor, insulin-like growth factor-I, interleukin-6, and acute phase proteins in patients with colorectal liver metastases treated with partial hepatectomy or cryosurgery

BACKGROUND/AIMS

The aim of the study was to compare the serum response of regeneration factors and acute phase proteins in patients treated with partial hepatectomy or cryosurgery.

METHODS

The responses of serum hepatocyte growth factor (HGF), insulin-like growth factor-I (IGF-I) (free and total), interleukin-6 (IL-6) and the acute phase proteins, C-reactive protein (CRP) and serum amyloid A (SAA) were examined in patients with colorectal liver metastases treated with partial hepatectomy (n = 14) or cryosurgery (n = 10).

RESULTS

In both groups, IL-6 peak levels at the end of the operation were followed by peak levels at day 1 for HGF and CRP. SAA peak levels occurred on day 1 (hepatectomy group) and on day 4 (cryo group). The total HGF, IGF-I, and IL-6 responses were comparable in both groups. CRP and SAA responses were higher in the patients treated with cryosurgery than in patients after hepatectomy. Free IGF-I trough levels were lower in partial hepatectomy patients than in cryosurgery patients.

CONCLUSIONS

In patients with colorectal liver metastases the responses of the regenerating factors HGF, IGF-I, and IL-6 are comparable to those in patients treated with partial hepatectomy. Upregulation of acute phase protein production is higher in patients after cryosurgery than in patients after partial hepatectomy.

Differential regenerative response and expression of growth factors following hepatectomy of variable extent in rats

AIMS/BACKGROUND

Liver regeneration is a physiological mechanism which leads to restoration of the hepatic parenchyma following hepatectomy or toxic injury. This process is mediated by a wide variety of cytokines and growth factors. The aim of the present study was to evaluate the influence of hepatectomy extent on the levels of intrahepatic mRNAs for cell-cycle markers and growth factors in rats submitted to a 30%, two-third or 80% hepatectomy.

METHODS

Cyclins, thymidine kinase and growth factors mRNA levels were quantitatively assessed by RT-PCR at different time points post-hepatectomy (2h, 6h, 12h, days 1, 2, 6).

RESULTS

As compared with a two-third hepatectomy, cyclins and thymidine kinase mRNA levels were increased but with a delayed peak at day 2 in the 80% hepatectomy group and showed a progressive increase until day 6 in the 30% hepatectomy group; mRNA levels for HGF or TGFalpha were increased with a delayed peak at 12 h or day 2 in the 80% hepatectomy group, respectively and this delay was more pronounced in the 30% hepatectomy group with a peak at day 1 or day 6.

CONCLUSION

A regenerative response occurs whatever the extent of hepatectomy but the course of regeneration and expression of growth factors differs according to the volume of resected liver. A better knowledge of these events could improve the clinical results of hepatic resection for primary or metastatic liver disease.