Selective portal clamping to minimize hepatic ischaemia-reperfusion damage and avoid accelerated outgrowth of experimental colorectal liver metastases

Downregulation of DNA repair proteins and increased DNA damage in hypoxic colon cancer cells is a therapeutically exploitable vulnerability

Surgical removal of colorectal cancer (CRC) liver metastases generates areas of tissue hypoxia. Hypoxia imposes a stem-like phenotype on residual tumor cells and promotes tumor recurrence. Moreover, in primary CRC, gene expression signatures reflecting hypoxia and a stem-like phenotype are highly expressed in the aggressive Consensus Molecular Subtype 4 (CMS4). Therapeutic strategies eliminating hypoxic stem-like cells may limit recurrence following resection of primary tumors or metastases.

Here we show that expression of DNA repair genes is strongly suppressed in CMS4 and inversely correlated with hypoxia-inducible factor-1 alpha (HIF1α) and HIF-2α co-expression signatures. Tumors with high expression of HIF signatures and low expression of repair proteins showed the worst survival. In human tumors, expression of the repair proteins RAD51, KU70 and RIF1 was strongly suppressed in hypoxic peri-necrotic tumor areas. Experimentally induced hypoxia in patient derived colonospheres in vitro or in vivo (through vascular clamping) was sufficient to downregulate repair protein expression and caused DNA damage. Hypoxia-induced DNA damage was prevented by expressing the hydroperoxide-scavenging enzyme glutathione peroxidase-2 (GPx2), indicating that reactive oxygen species mediate hypoxia-induced DNA damage. Finally, the hypoxia-activated prodrug Tirapazamine greatly augmented DNA damage and reduced the fraction of stem-like (Aldefluor^bright) tumor cells in vitro, and in vivo following vascular clamping.

We conclude that decreased expression of DNA repair proteins and increased DNA damage in hypoxic tumor areas may be therapeutically exploited with hypoxia-activated prodrugs, and that such drugs reduce the fraction of Aldefluor^bright (stem-like) tumor cells.

Hepatic vascular inflow occlusion is associated with reduced disease free survival following resection of colorectal liver metastases

BACKGROUND

Hepatic vascular inflow occlusion (VIO) can be applied during resection of colorectal liver metastases (CRLM) to control intra-operative blood loss, but has been linked to accelerated growth of micrometastases in experimental models. This study aimed to investigate the effects of hepatic VIO on disease-free and overall survival (DFS and OS) in patients following resection for CRLM.

METHODS

All patients who underwent liver resection for CRLM between January 2006 and September 2015 at our center were analyzed. Hepatic VIO was performed if deemed indicated by the operating surgeon and severe ischemia was defined as ≥20 min continuous or ≥45 min cumulative intermittent VIO. Cox regression analysis was performed to identify predictive factors for DFS and OS.

RESULTS

A total of 208 patients underwent liver resection for CRLM. VIO was performed in 64 procedures (31%), and fulfilled the definition of severe ischemia in 40 patients. Patients with severe ischemia had inferior DFS (5-year DFS 32% vs. 11%, P < 0.01), and inferior OS (5-year OS 37% vs. 64%, P < 0.01). At multivariate analysis, a high clinical risk score (Hazard ratio (HR) 1.60 (1.08-2.36)) and severe ischemia (HR 1.89 (1.21-2.97)) were independent predictors of worse DFS. Severe ischemia was not an independent predictor of OS.

CONCLUSION

The present cohort study suggests that prolonged hepatic VIO during liver resection for CRLM was associated with reduced DFS. A patient-tailored approach seems advisable although larger studies should confirm these findings.

Actual incidence and long-term consequences of posthepatectomy liver failure after hepatectomy for colorectal liver metastases

INTRODUCTION

Posthepatectomy liver failure (PHLF) is a severe complication after hepatectomy for colorectal liver metastases. This study evaluated its actual incidence and its effects on short- and long-term overall survival (OS) in a specialized center.

MATERIALS AND METHODS

Between 2006 and 2008, 193 patients who underwent 232 hepatectomies (147 minor and 85 major) for colorectal liver metastasis were studied prospectively. Hepatectomy was performed if the remnant liver volume was >0.5% of body weight. Uni- and multivariate analyses on OS after all hepatectomies (n = 232) or major resection only (n = 85) were then performed on pre-, intra-, and postoperative (including pathological) data to determine the consequences of PHLF by comparison with those of other intra- and postoperative events.

RESULTS

The 3-month postoperative mortality rate was 0.8%. PHLF was observed in six patients (7%) after major hepatectomy and in one (0.6%) after minor hepatectomy. With a 25-month follow-up, the 2-year OS rate was 84%. Preoperatively, pulmonary metastasis was the only determinant of OS. Intra- and postoperatively, four factors were determinant of OS: PHLF (risk ratio [RR] = 3.84, P = .04), mental confusion (RR = 3.11, P = .006), fluid collection (RR = 2.9, P = .01) and transfusion (RR = 2.27, P = .009). After major hepatectomy, only PHLF (RR = 4.14, P = .01) and confusion (RR = 3.6, P = .02) were identified.

CONCLUSION

With improvements in postoperative management, PHLF was found to be less responsible for 3-month mortality but remains an event that exerts a major impact on 2-year survival.

Hepatic pedicle clamping does not worsen survival after hepatic resection for colorectal liver metastasis: results from a systematic review and meta-analysis

BACKGROUND

Hepatic pedicle clamping (HPC) has been demonstrated to be effective for short-term outcomes during hepatic resection. However, HPC-induced hepatic ischemia/reperfusion injury can accelerate the outgrowth of hepatic micrometastases in experimental studies. The conclusive evidence regarding effects of HPC on long-term patient outcomes after hepatic resection for colorectal liver metastasis (CRLM) has not been determined.

METHODS

A comprehensive electronic literature search was performed to identify studies evaluating the oncological effects of HPC after hepatic resection for CRLM. The main outcome measures were intrahepatic recurrence (IHR), disease-free survival (DFS), and overall survival (OS). A meta-analysis was performed using the random-effects models to compute odds ratio (OR) along with 95% confidence intervals (CI).

RESULTS

Four studies, with a total of 2,114 patients (73.7% HPC, 26.3% non-HPC), matched the inclusion criteria. Meta-analyses revealed that IHR (OR 0.88; 95% CI 0.69-1.11; P = 0.27), DFS (OR 0.88; 95% CI 0.70-1.10; P = 0.27) and OS (OR 0.99; 95% CI 0.79-1.24; P = 0.90) did not differ significantly between the HPC and non-HPC groups.

CONCLUSIONS

This meta-analysis provides persuasive evidence that HPC during hepatic resection for CRLM has no significant adverse oncological outcomes. HPC should be considered an option during parenchymal liver resection from current available evidence.

Is there any benefit from expanding the criteria for the resection of hepatocellular carcinoma in cirrhotic liver? Experience from a developing country

BACKGROUND

Patients with large-size (>10 cm) hepatocellular carcinoma (HCC) in Child B cirrhosis are usually excluded from curative treatment, i.e., hepatic resection, because of marginal liver function and poor outcome. This study was designed to evaluate the feasibility of the radiofrequency (RF)-assisted sequential "coagulate-cut liver resection technique" in expanding the criteria for resection of large HCC in cirrhotic livers with impaired liver function.

METHODS

Forty patients with Child-Pugh A or B cirrhosis underwent liver resection from December 1, 2001 to December 31, 2008. Of these, 20 patients (13 Child-Pugh A and 7 Child-Pugh B) with advanced stage HCC (stage B and C according to Barcelona-Clinic Liver Cancer Group) underwent major liver resection. The two groups were comparable in terms of patient age, liver cirrhosis etiology, tumor number, and size.

RESULTS

All resections were performed without the Pringle maneuver. There was no significant difference found between the two groups regarding resection time, perioperative transfusion, postoperative complications, hospital stay, and day 7 values of hemoglobin and liver enzymes. Likewise, there was no significant difference found in the overall survival between Child A and Child B patients who underwent major liver resection

CONCLUSIONS

RF-assisted sequentional "coagulate-cut liver resection technique" may be a viable alternative for management of patients with advanced HCC in cirrhotic liver with impaired function.

Hepatic ischaemia-reperfusion injury from bench to bedside

BACKGROUND

Vascular occlusion to prevent haemorrhage during liver resection causes ischaemia-reperfusion (IR) injury. Insights into the mechanisms of IR injury gathered from experimental models have contributed to the development of therapeutic approaches, some of which have already been tested in randomized clinical trials.

METHODS

The review was based on a PubMed search using the terms 'ischemia AND hepatectomy', 'ischemia AND liver', 'hepatectomy AND drug treatment', 'liver AND intermittent clamping' and 'liver AND ischemic preconditioning'; only randomized controlled trials (RCTs) were included.

RESULTS

Twelve RCTs reported on ischaemic preconditioning and intermittent clamping. Both strategies seem to confer protection and allow extension of ischaemia time. Fourteen RCTs evaluating pharmacological interventions, including antioxidants, anti-inflammatory drugs, vasodilators, pharmacological preconditioning and glucose infusion, were identified.

CONCLUSION

Several strategies to prevent hepatic IR have been developed, but few have been incorporated into clinical practice. Although some pharmacological strategies showed promising results with improved clinical outcome there is not sufficient evidence to recommend them.

Clinical features of hepatocellular carcinoma developing extrahepatic recurrences after curative resection

BACKGROUND

Few details of the clinical features of hepatocellular carcinoma (HCC) developing extrahepatic recurrence after a curative resection have been published. The purpose of this study was to clarify the clinicopathologic findings of patients with HCC who experienced extrahepatic metastases.

METHODS

Clinicopathologic data were available for 119 patients who underwent an R0 resection for HCC. Twenty-three patients who developed extrahepatic metastases during the follow-up period were compared with the patients who remained free from recurrence for at least 5 years after resection (n = 21) or with only intrahepatic recurrences (n = 75).

RESULTS

Patients with extrahepatic recurrences were more likely to have their tumor macro- or microscopically invading the tumor capsule (P < 0.001) and hepatic vein (P = 0.003), a high AFP concentration (P = 0.014), and advanced TNM stage (P = 0.006) than the other patients. As for treatment-related variables, inflow vessel occlusion during hepatectomy was less frequently associated with extrahepatic recurrences than if it were not performed (P < 0.001). By multivariate analysis, absence of tumor invasion to the capsule (relative risk [RR] = 0.080; P = 0.023) or to the hepatic vein (RR = 0.108; P = 0.014) and a hepatectomy in which inflow vessel occlusions were performed (RR = 0.161; P = 0.004) were selected as independent factors for reducing extrahepatic recurrences after a hepatectomy.

CONCLUSION

In HCC patients, the control of intrahepatic recurrences and extrahepatic recurrences after a hepatectomy is important to improve the prognosis. Inflow occlusion during the hepatectomy may reduce HCC metastases to extrahepatic sites.

Ageing and hepatic steatosis exacerbate ischemia/reperfusion-accelerated outgrowth of colorectal micrometastases

BACKGROUND

Ischemia/reperfusion (I/R) injury is frequently encountered during hepatic surgery. We recently showed that I/R accelerates the outgrowth of pre-established colorectal micrometastases. The aim of this study was to assess the influence of ischemia time, gender, age, and liver steatosis on the accelerated outgrowth of colorectal metastases following I/R.

METHODS

Five days after tumor cell inoculation, mice were subjected to 20, 30 or 45 min of left lobar I/R. To assess the influence of age, gender, and liver steatosis on I/R-accelerated tumor growth, we compared old with young mice, male with female mice, and mice with healthy livers with mice with steatotic livers. Endpoints were extent of tissue necrosis and tumor growth.

RESULTS

With increasing ischemia times, tissue necrosis and I/R-accelerated tumor growth increased, with a significant stimulatory effect at 30 and 45 min of ischemia. I/R-stimulated outgrowth of micrometastases was further increased by 33% in aged mice and by 42% in steatotic livers and was associated with increased tissue necrosis. In female mice tissue necrosis had decreased by 47% and tumor growth was reduced in both control and clamped liver lobes. The stimulatory effect of I/R on metastasis outgrowth was similar in male and female mice.

CONCLUSIONS

I/R-accelerated outgrowth of colorectal micrometastases largely depends on the duration of the ischemic period, with a safe upper limit of 20 min in mice. The stimulatory effects of I/R on tumor growth are exacerbated in aged mice and in steatotic livers.

Protective effects of ischemic preconditioning and application of lipoic acid prior to 90 min of hepatic ischemia in a rat model

AIM: To compare different preconditioning strategies to protect the liver from ischemia/reperfusion injury focusing on the expression of pro- and anti-apoptotic proteins. Interventions comprised different modes of ischemic preconditioning (IP) as well as pharmacologic pretreatment by α-lipoic acid (LA).

METHODS: Several groups of rats were compared: sham operated animals, non-pretreated animals (nt), animals receiving IP (10 min of ischemia by clamping of the portal triad and 10 min of reperfusion) prior to sustained ischemia, animals receiving selective ischemic preconditioning (IPsel, 10 min of ischemia by selective clamping of the ischemic lobe and 10 min of reperfusion) prior to sustained ichemia, and animals receiving 500 μmol α-LA injected i.v. 15 min prior to the induction of 90 min of selective ischemia.

RESULTS: Cellular damage was decreased only in the LA group. TUNEL-positive hepatocytes as well as necrotic hepatocyte injury were also decreased only by LA (19 ± 2 vs 10 ± 1, P < 0.05 and 29 ± 5 vs 12 ± 1, P < 0.05). Whereas caspase 3- activities in liver tissue were unchanged, caspase 9- activity in liver tissue was decreased only by LA pretreatment (3.1 ± 0.3 vs 1.8 ± 0.2, P < 0.05). Survival rate as the endpoint of liver function was increased after IP and LA pretreatment but not after IPsel. Levels of lipid peroxidation (LPO) in liver tissue were decreased in the IP as well as in the LA group compared to the nt group. Determination of pro- and anti-apoptotic proteins showed a shift towards anti-apoptotic proteins by LA. In contrast, both our IP strategies failed to influence apototic cell death.

CONCLUSION: IP, consisting of 10 min of ischemia and 10 min of reperfusion, protects only partly against ischemia/reperfusion injury of the liver prior to 90 min of selective ischemia. IPsel did not influence ischemic tolerance of the liver. LA improved tolerance to ischemia, possibly by downregulation of pro-apoptotic Bax.