Scanning electron microscopy study of the blood supply of human colorectal liver metastases

Targeting epigenetically maladapted vascular niche alleviates liver fibrosis in nonalcoholic steatohepatitis

[Figure: see text].

Transportal Radioembolization as Salvage Hepatocellular Carcinoma Therapy to Maintain Liver Transplant Candidacy

A 53-year-old woman with chronic hepatitis B and multifocal hepatocellular carcinoma was unable to receive transarterial radioembolization and had disease progression despite multiple chemoembolizations and systemic chemotherapy. Transportal radioembolization (TPRE) to maintain transplant candidacy was performed. Two lesions (1.7 cm, 1.4 cm) were treated with a single session of TPRE. Imaging performed at 4 months after TPRE demonstrated complete response in one lesion and stable disease in the other. This case illustrates TPRE as a salvage therapy for hepatocellular carcinoma in select patients.

Target hepatic artery regional chemotherapy and bevacizumab perfusion in liver metastatic colorectal cancer after failure of first-line or second-line systemic chemotherapy

Colorectal cancer liver metastasis (CRLM) is a refractory disease after failure of first-line or second-line chemotherapy. Bevacizumab is recommended as first-line therapy for advanced colorectal cancer, but is unproven in CRLM through the hepatic artery. We report favorable outcomes with targeted vessel regional chemotherapy (TVRC) for liver metastatic gastric cancer. TVRC with FOLFOX and bevacizumab perfusion through the hepatic artery was attempted for CRLM for efficacy and safety evaluation. In a single-institution retrospective observational study, 246 patients with CRLM after at least first-line or second-line failure of systemic chemotherapy received TVRC with FOLFOX (i.e. oxaliplatin, leucovorin, and 5-fluorouracil). Of 246 patients, 63 were enrolled into two groups: group 1 (n=30) received bevacizumab and TVRC following tumor progression during previous TVRC treatments; group 2 (n=33) received TVRC plus bevacizumab for CRLM on initiating TVRC. There were no significant differences in the median survival time (14.7 vs. 13.2 months, P=0.367), although the median time to progression was significant (3.3 vs. 5.5 months, P=0.026) between groups. No severe adverse events related to TVRC plus bevacizumab perfusion occurred. Target vessel regional chemotherapy with FOLFOX plus bevacizumab perfusion through the hepatic artery was effective and safe in CRLM. The optimal combination of TVRC and bevacizumab needs further confirmation in future phase II-III clinical trials.

Relationship between CT volumetric measurements and Doppler perfusion indices in gastrointestinal liver metastasis

PURPOSE

This study investigated how the volume of hepatic metastatic lesions can affect liver haemodynamics and whether these perfusion parameters may help to differentiate benign and malignant liver lesions.

MATERIALS AND METHODS

The Doppler perfusion index (DPI the ratio of arterial to total liver blood flow) was measured in 46 patients aged 29-83 years, exhibiting up to four focal hyperechoic liver lesions at ultrasound examination. They comprised histopathologically proven liver metastasis of colorectal (19 cases) and gastric (10 cases) adenocarcinoma without local recurrence at the site of the previously resected primary tumour, along with 17 subjects with haemangioma. All patients underwent volumetric assessment using multislice computed tomography to calculate total volume of hepatic lesions.

RESULTS

The mean DPI of patients with colorectal (36 ± 2 %) and gastric (39 ± 6 %) metastasis was significantly higher than those with haemangioma (14 ± 2 %) (both p < 0.001), whereas metastatic groups did not exhibit any difference in terms of mean DPI. Statistically significant correlations were found between DPI values and calculated total volume of lesions in patients with colorectal and gastric metastasis (r = 0.55, p = 0.01 and r = 0.85, p = 0.002, respectively) while this correlation was not demonstrated in the haemangioma group. Simple linear regression analysis revealed that every 1 cm(3) increment in total volume of metastatic lesions increased DPI by 0.2 % [95 % confidence interval (CI) 0.1-0.3, p = 0.001].

CONCLUSION

Doppler perfusion index alterations are directly correlated with total volume of metastatic deposits, and DPI measurement can be a valuable method to distinguish haemangioma from hyperechoic colorectal and gastric metastatic lesions.

Development of arterial blood supply in experimental liver metastases

In this study, we present a mechanism for the development of arterial blood supply in experimental liver metastases. To analyze the arterialization process of experimental liver metastases, we elucidated a few key questions regarding the blood supply of hepatic lobules in mice. The microvasculature of the mouse liver is characterized by numerous arterioportal anastomoses and arterial terminations at the base of the lobules. These terminations supply one hepatic microcirculatory subunit per lobule, which we call an arterial hepatic microcirculatory subunit (aHMS). The process of arterialization can be divided into the following steps: 1) distortion of the aHMS by metastasis; 2) initial fusion of the sinusoids of the aHMS at the tumor parenchyma interface; 3) fusion of the sinusoids located at the base of the aHMSs, which leads to the disruption of the vascular sphincter (burst pipe); 4) incorporation of the dilated artery and the fused sinusoids into the tumor; and 5) further development of the tumor vasculature (arterial tree) by proliferation, remodeling, and continuous incorporation of fused sinusoids at the tumor-parenchyma interface. This process leads to the inevitable arterialization of liver metastases above the 2000- to 2500-mum size, regardless of the origin and growth pattern of the tumor.

Right portal vein embolization before right hepatectomy for unilobar colorectal liver metastases reduces the intrahepatic recurrence rate

AIM

To assess the effect of portal vein embolization (PVE) on intrahepatic recurrence rate after right hepatectomy for unilobar colorectal liver metastases (CLM).

SUMMARY AND BACKGROUND

Recent research suggests that CLM could spread retrogradely through the portal vein. PVE may reduce tumor shedding by the occlusion of distal portal branches. However, no study reported the clinical effect of PVE on intrahepatic recurrence after CLM resection.

PATIENTS AND METHODS

Between 1995 and 2003, 44 patients requiring a right hepatectomy for unilobar CLM were operated in our institution. Right hepatectomy was performed after PVE in 23 patients (group A) and without PVE in 21 (group B). Surgical outcome and site of recurrence were analyzed.

RESULTS

The postoperative mortality was nil. Overall morbidity and transitory liver failure rates were similar in groups A and B (43.4% and 17.3% vs. 33.3% and 14.2%, respectively). The 3- and 5-year overall survival rates did not differ in group A and B patients (61.2% and 43.7% vs. 49.7% and 35.5%, respectively; P = 0.862). The disease-free survival rate was similar in both groups. Thirty patients (68.2%) developed recurrences. Recurrences were intrahepatic in 22 patients (50%) and extrahepatic in 27 (61.3%). Intrahepatic recurrence rate was significantly lower in group A compared with group B (26.0% vs. 76.1% respectively; P < 0.001). PVE, number of CLM, and administration of neoadjuvant chemotherapy were independent prognostic factors for intrahepatic recurrences.

CONCLUSION

This study showed that PVE reduces intrahepatic recurrence rate after right hepatectomy for unilobar CLM.

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.

Tumor growth-promoting cellular host response during liver atrophy after portal occlusion

BACKGROUND/AIMS

Clinical observations suggest cancer progression after preoperative segmental portal vein occlusion, a procedure to prevent liver failure after major hepatic resections. The aim of this study was to determine whether portal occlusion induces host reactions which promote cancer invasion and angiogenesis.

METHODS

The rat model of portal branch ligation (PBL) was compared with partial hepatectomy (PH) and sham operation (SO) and evaluated for the expression of heat shock protein-70 (hsp70), heme oxygenase-1 (hmox1), early growth response gene-1 (Egr-1) and urokinase-type plasminogen activator (uPA), its inhibitor (PAI-1) and receptor (uPAR).

RESULTS

Portal deprivation after PBL was associated with a regression of liver tissue to 25% of its original mass within 8 days with only modest fibrotic changes. During the progression of atrophy, there were significant inductions of hsp70-, hmox1- and Egr-1-mRNA in comparison with regenerating liver tissue. PAI-1-specific mRNA was transiently elevated at 3 - 48 h after PBL in the atrophying lobes, whereas uPA and uPAR were unaffected in comparison with PH or SO.

CONCLUSION

Hepatic atrophy caused by PBL is associated with increased expression of genes known to promote tumor growth. These host events represent a possible explanation for the tumor progression after portal occlusion and require further evaluation.

Focal hyperthermia produces progressive tumor necrosis independent of the initial thermal effects

Focal hyperthermia, produced using laser, radio frequency, and microwave, is used to treat liver tumors. The exact mechanisms of tissue destruction using focal hyperthermia are, however, unknown. Clinical and experimental studies suggest a progression of injury after cessation of the initial heat stimulus. This study investigates the mechanisms and time sequence of progressive tissue necrosis induced using focal hyperthermia in a murine model of colorectal liver metastases. Focal hyperthermia produced using a neodymium-yttrium aluminum garnet (Nd-YAG) laser source was applied to the normal liver and colorectal cancer liver metastases in inbred male CBA strain mice. The extent of direct lethal thermal injury was assessed histochemically using vital stain for nicotinamide adenine dinucleotide (NADH) diaphorase immediately after laser application. Tissue injury at subsequent time points was assessed using both NADH diaphorase staining and routine histology to determine the temporal relationship between tissue necrosis and time. Thermal injury occurring immediately after the application of 100 joules of energy was greater in the tumor tissue than in the normal liver (mean [standard error of the mean (SEM)]), measuring 23.5 (3.4) and 16.3 (2.6) mm(3), respectively (P=0.046), despite similar tissue temperature profiles. There was a significant increase in tissue necrosis after initial injury that was greater in the normal liver than in the tumor tissue. In the normal liver, the peak volume of necrosis was 137.4 (9.8) mm(3) and occurred at 3 days, whereas in the tumor tissue the peak was 49.0 (3.5) mm(3) at 4.5 days (P < 0.001). Focal hyperthermia produces tissue necrosis that occurs in two phases. The first phase is caused by the direct lethal thermal injury followed by a second phase involving a progression of necrosis beyond the initial thermal effects. The normal liver and the tumor tissue responded differently to focal hyperthermia. In the tumor tissue, the direct injury is more pronounced, whereas the progression of injury is more rapid and extensive in the normal liver.

Progressive microvascular injury in liver and colorectal liver metastases following laser induced focal hyperthermia therapy

BACKGROUND AND OBJECTIVES

Focal hyperthermia by laser or radiofrequency is currently the preferred method for local ablation of liver tumors. The underlying mechanism of action of focal hyperthermia, in particular the relationship between the microvascular and tissue effect is uncertain and was investigated in a murine model.

STUDY DESIGN/MATERIALS AND METHODS

Focal hyperthermia produced by a Neodymium-Yttrium-Aluminium-Garnet laser (wavelength 1,064 nm) was applied to the normal liver and colorectal cancer liver metastases in inbred male CBA strain mice at 2 W for 50 seconds (100 J). Tissue injury was assessed at 0, 24, 48, 72, 120, and 168 hours following therapy by measurements of necrosis in tissue sections stained for nicotinamide adenine dinucleotide (NADH) diaphorase activity. Characteristics of microvascular injury were assessed at the various time points by scanning electron microscopy (SEM) of vascular resin casts, Laser Doppler flowmetry, and confocal in vivo microscopy.

RESULTS

Focal hyperthermia produced progressive tissue and vascular injury. There was an initial reduction in blood flow and increased vascular permeability in the microcirculation of both tumor and liver tissue immediately following heat application as assessed by laser Doppler flowmetry and confocal in vivo microscopy, respectively. SEM of vascular casts showed heterogeneous regions of microvascular injury immediately following heat application. The extent of initial vascular disruption or occlusion on SEM of vascular resin casts (mean+/-SE) was significantly less than the tissue necrosis in liver (1.9+/-0.1 mm vs. 3.0 mm+/-0.2 mm P<0.001), but was equivalent to the tissue injury in tumor tissue (3.5 mm+/-0.2 mm vs. 3.6 mm+/-0.1 mm P = 0.907). This was followed by a progressive increase in both microvascular and tissue injury in liver and tumor that peaked by 72 hours following treatment. The peak microvascular injury and tissue damage in liver (6.6 mm+/-0.2 and 6.3 mm+/-0.2 mm, respectively) was significantly greater than the extent of microvascular and tissue damage in tumors (4.8 mm+/-0.2 mm and 4.5 mm+/-0.2 mm, respectively) (P<0.001). The progression of microvascular injury in liver and tumor at times preceded the tissue injury.

CONCLUSION

Focal hyperthermia produces both progressive microvascular and tissue damage in liver and colorectal liver metastases. An increase in tissue injury following focal hyperthermia may be a direct result of progressive microvascular damage. Tumor vessels appear more susceptible to direct focal hyperthermia destruction than liver sinusoids. The liver sinusoids are however more susceptible to progressive damage or occlusion following the initial laser thermal stimulus.