Partial hepatectomy augments the liver's antitumor response

Postoperative liver regeneration does not elicit recurrence of colorectal cancer liver metastases after major hepatectomy

BACKGROUND AND OBJECTIVES

Recurrence is a frequent concern in curatively resected CRC liver metastases. Translational research suggests that regeneration upon hepatectomy may also alleviate metastatic recurrence; however, the significance in patients is unclear. We therefore sought to study the effect of liver regeneration on tumor recurrence in patients.

METHODS

In this retrospective cohort study, we included 58 out of 186 potentially eligible patients from our prospectively maintained database of CRC liver metastasis patients between 2001 and 2012 with a median follow-up of 42 months who underwent a formal right or left hemihepatectomy. Liver regeneration in CT volumetry was correlated with recurrence of CRC liver metastases and overall survival.

RESULTS

Liver regeneration increased up to 14 months to 21.0% for left and 122.6% for right hemihepatectomy, respectively, with comparable final volumes. Regeneration was independent of initial tumor stage, number of metastases, and preoperative chemotherapy. Patients with lower liver regeneration showed earlier recurrence of CRC liver metastases (p = 0.006). Overall survival did not differ in patients with weak versus strong liver regeneration.

CONCLUSIONS

The extent of liver regeneration after major hepatectomy does not impede overall survival. Therefore, our data encourage aggressive therapeutical regimes for CRC liver metastases involving major hepatectomies as part of a curative approach.

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.

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.

Liver regeneration and tumour stimulation: implications of the renin-angiotensin system

Liver resection is the most effective treatment for primary liver tumours and metastasis to the liver, and remains the only potentially long-term curative therapy for patients with colorectal cancer (CRC) liver metastases. Nevertheless, there is a significant incidence of tumour recurrence following liver resection. Cellular and molecular changes resulting from resection and the subsequent liver regeneration process may influence the kinetics of tumour growth, contributing to recurrence. Although commonly associated with the systemic homeostasis of blood pressure, fluid and electrolyte, the renin-angiotensin system (RAS) has recently been shown to play a role in regulating cell proliferation, apoptosis and angiogenesis in local organs as well as in malignancies. An electronic search of the English literature on the role of the RAS in liver regeneration and tumourigenesis was performed using PubMed, with additional relevant articles sourced from reference lists. Studies have shown that the blockade of the RAS pathway stimulates liver regeneration and inhibits tumour progression. An understanding of the role of RAS in liver regeneration and tumourigenesis may enable alternative strategies to improve patient outcome and survival after liver resection. This review will discuss the role of the RAS in liver regeneration and in tumour recurrence post-liver resection. The potential of the RAS as a novel therapeutic target for CRC liver metastases patients undergoing liver resection will be outlined.

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.

Use of bioluminescence imaging to detect enhanced hepatic and systemic tumor growth following partial hepatectomy in mice

BACKGROUND

The impact of partial hepatectomy on intra-hepatic and distant tumor growth is a matter of controversy. Utilizing a highly sensitive tumor imaging strategy, we sought to demonstrate whether this growth-acceleration occurs, and to develop an animal model with which to investigate potential therapeutic strategies.

METHODS

Mice bearing constitutively-active luciferase-expressing tumor cells were subjected to either 70% partial hepatectomy (PH; n=10) or a sham operation (n=11). Mice were sacrificed 14 days later and remnant livers (or anatomic equivalents in the control group) and lungs harvested for bioluminescence detection.

RESULTS

Remnant liver weights were significantly increased in PH compared to equivalent lobes in sham-operated animals (t-test; p=0.005). Tumor burden as measured by bioluminescence was significantly higher in both liver and lung specimens in the PH group (Wilcoxon's Rank Sum test; p=0.01 and 0.004, respectively).

CONCLUSIONS

Following PH, enhanced metastatic growth was depicted regionally and systemically with bioluminescence imaging providing an objective measure of tumor burden. This preclinical model can help to identify adjuvant therapies that can influence both tumor growth and liver regeneration.

Major but not minor hepatectomy accelerates engraftment of extrahepatic tumor cells

BACKGROUND

The effect of hepatectomy and hepatic regeneration on intra- and extrahepatic tumor growth is still controversially discussed. Herein we studied the effect of minor (30%) or major (70%) hepatectomy on engraftment of extrahepatic tumor cells, and the role of tumor neovascularization and tumor cell migration.

METHODS

Green fluorescent protein (GFP)-transfected CT26.WT colorectal cancer cells were implanted in dorsal skinfold chambers of syngeneic BALB/c mice. Animals underwent 30% (30%Phx, n = 8) or 70% hepatectomy (70%Phx, n = 8). Sham-operated animals served as controls (n = 8). Angiogenesis and neovascularization as well as tumor cell migration, proliferation and growth were studied over 14 days using intravital fluorescence microscopy, histology and immunohistochemistry.

RESULTS

After both minor and major hepatectomy tumor proliferating cell nuclear antigen (PCNA) expression increased significantly (P < 0.05) when compared with nonhepatectomized controls. However, only major but not minor hepatectomy accelerated neovascularization (P < 0.05) and tumor cell migration (P < 0.05). This was associated with a significantly (P < 0.05) enhanced tumor growth after 70%Phx when compared with 30%Phx and controls. The rate of apoptotic cell death was not affected by major or minor hepatectomy.

CONCLUSION

Regeneration after major hepatectomy accelerates extrahepatic tumor cell engraftment, most probably by acceleration of neovascularization and induction of tumor cell migration.

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.

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.

Major hepatic resection may suppress the growth of tumours remaining in the residual liver

Little is known as to how hepatectomy is associated with the growth of hepatic tumours, which may reside in the remaining liver after curative resection for hepatocellular carcinoma. Using an intra-hepatic tumour implantation model in rats, the effects of hepatectomy on tumour growth in the remaining liver were investigated. On post-operative day 7, the tumour weight in the remaining liver following 30% hepatectomy was 0.321+/-0.058 g (mean +/- SD) which was significantly greater than that (0.245+/-0.040 g) in sham operations (P<0.05). However, the tumour weight (0.156+/-0.067 g) in the remaining liver following 60% hepatectomy was significantly lower than that in sham animals (P< 0.005). The number of TdT-mediated dUTP nick-end labelling (TUNEL) positive tumour cells was significantly increased in 60% hepatectomy as compared with the sham and 30% hepatectomy group. The mRNA expression of TGF-beta1, TNF-alpha and Fas in the tumour portion of 60% hepatectomy, was higher than that in 30% hepatectomy group. Plasma levels of TGF-beta1 were inversely correlated with intra-hepatic tumour weights. These results suggest that major hepatic resection may lead to an increased induction of apoptosis for the remaining hepatic tumour.

Minimal liver resection strongly stimulates the growth of human colon cancer in the liver of nude mice

Partial hepatectomy has been widely employed in clinical practice as the therapy of choice for primary and metastatic liver tumors. However, the recurrence rate after the treatment remains high, which is most likely due to the growth of residual microscopic lesions. Previous studies in murine models demonstrated that a 70% hepatectomy significantly accelerated the growth of ectopically implanted tumors. In this study, we reported the effect of partial hepatectomy on the growth of two human colon cancers (Co-3 and AC3603) implanted in the liver of nude mice using the technique of surgical implantation of histologically intact tumor tissue. Our results showed a dramatic acceleration of tumor growth following 30% partial hepatectomy, which resembles clinical procedures. Tumor volumes were assessed with calipers on day-15 by abdominal palpation and on day-30 at autopsy by direct measurement. For both Co-3 and AC3603, tumor volumes in the hepatectomized animals were significantly larger than the control at the above two time points (P < 0.001). The results demonstrate the stimulating effect of partial hepatectomy directly on the tumor growth in the liver, in contrast to previous studies on ectopic tumors. Furthermore, since conservative partial hepatectomy (30%) is normally used in clinical practice for surgical treatment of liver metastasis, the animal models presented here should be useful for the clinical investigation of the high recurrence rate of liver metastasis following partial hepatectomy.

The effect of partial hepatectomy on tumor growth in rats: in vivo and in vitro studies

Residual tumor in the remnant liver after partial hepatectomy (PH) for colorectal liver metastases is a serious clinical problem. This fact is reflected by the high number of recurrences after potentially curative liver resections. Liver regeneration, it appears, might influence the growth of remaining micrometastases in the liver. Using rats, we demonstrated enhancement of growth of a syngeneic colon carcinoma (CC 531) in the remnant liver after 70% PH. Fourteen days after PH, tumor weights in the liver were twice as high as those of sham-operated rats. This difference in tumor weight was not found in extrahepatic tumors. In vitro experiments did not show stimulation of cultured CC 531 cells by portal or systemic serum withdrawn 24 hours or 14 days after hepatectomy as compared with sera obtained after sham operation. Co-cultures of CC 531 cells and hepatocytes (in ratios of 1:10 or 1:1) demonstrated a higher 3H-thymidine incorporation than was the case in separately cultured cells. In co-cultures, bromodeoxyuridine (BrdU) incorporation in DNA was found primarily in CC 531 cells and rarely in hepatocytes. Cell density appeared to be of influence on 3H-thymidine incorporation in co-cultures. Hepatocytes were found to have a stimulating effect on CC 531 cells in low-density cultures, whereas high-density cultures exhibited an inhibiting effect after a culture time of 120 hours. These results show that, depending on cell density in co-cultures, a paracrine stimulating influence of hepatocytes on this type of colon carcinoma cells (CC 531) might be responsible for the increased tumor growth in vivo.

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

In an attempt to ascertain possible facilitation of tumor metastasis during liver regeneration after hepatectomy, a series of experiments in rats was carried out using the RBT-1 carcinoma. WKA rats were separated into three groups: Group A received a sham operation; Group B underwent one-third hepatectomy; and Group C underwent two-thirds hepatectomy. Three groups had viable tumor cells injected into the tail vein after treatment. Survival period and lung metastases were analysed 14 days after initial injection of tumor. When comparisons were made between all groups, survival was shown to be significantly shorter in Group C than Group A (P < 0.05). The number of metastatic nodules in the lungs was significantly increased in Group B (P < 0.05) and C (P < 0.01), compared to Group A and in Group C, compared with Group B (P < 0.05). These results suggest that facilitation of tumor metastasis during liver regeneration may be proportional to the extent of liver resection.

Tumour growth stimulation after partial hepatectomy can be reduced by treatment with tumour necrosis factor alpha

This study investigated whether partial hepatectomy enhances the growth of experimental liver metastases of colonic carcinoma in rats and whether treatment with recombinant human tumour necrosis factor (TNF) alpha can reduce this increased growth. Resection of 35 or 70 per cent of the liver was performed in inbred WAG rats, with sham-operated controls (five to eight animals per group). Immediately after surgery 5 x 10(5) CC531 colonic tumour cells were injected into the portal vein. After 28 days the animals were killed and the number of liver metastases counted. A 35 per cent hepatectomy induced a significant increase in the median number of liver metastases (28 versus 3 in controls), whereas a 70 per cent resection provoked excessive growth, consistently leading to more than 100 liver metastases and a significantly increased wet liver weight in all animals. TNF-alpha was given intravenously to rats following 70 per cent hepatectomy or sham operation in a dose of 160 micrograms/kg three times per week. This had only a marginal effect on tumour development in sham-operated rats but was very effective following partial hepatectomy (median 45 liver metastases). These observations confirm previous findings that surgical metastasectomy may act as a 'double-edged sword' by provoking outgrowth of dormant tumour cells and suggest that adjuvant treatment with TNF-alpha may be of benefit in patients undergoing resection of metastases.

Induction of serum borne immunomodulatory factors in B6C3F1 mice by carbon tetrachloride. Exposure to carbon tetrachloride produces an increase in B-cell number and function

Carbon tetrachloride exposure in mice induces a serum associated immunosuppressive factor(s) that inhibits T-cell dependent immune responses. The objective of the present studies was to characterize the immunomodulatory activity of serum isolated from carbon tetrachloride-treated mice on T-cell independent humoral immune responses. Direct addition of serum isolated from carbon tetrachloride-treated mice (500 mg/kg/day for 7 days) to naive spleen cell cultures enhanced the antibody forming cell response to lipopolysaccharide as compared to serum from naive or vehicle-treated mice. Enhanced antibody forming cell responses were also observed when spleen cells isolated from carbon tetrachloride-treated mice were sensitized with this T-cell independent antigen 24 h, but not 48 h or 72 h, following exposure of mice to one dose of 500 or 1000 mg/kg of carbon tetrachloride. Additionally, spleen weight and spleen:body weight ratio were increased in mice sensitized in vivo with sheep red blood cells 24 h after exposure to a single dose of carbon tetrachloride (500 or 1000 mg/kg) as compared to naive antigen sensitized mice and mice sensitized 48 and 72 h after exposure to carbon tetrachloride. Fluorescence activated cell sorting analysis indicated that daily exposure to carbon tetrachloride (250 or 500 mg/kg for 7 days) increased the percentage of B-cells in the spleen without altering the number of TH-cell or TC/S cell populations. Taken together, these results suggest that exposure to carbon tetrachloride induces a serum borne factor(s) that produces a modest increase in the functional activity and number of B-cells in the spleen.

Modulation of the expression of galactose-specific receptors on Kupffer cells after partial hepatectomy and zymosan stimulation

Partial hepatectomy (PH) and a single intravenous injection of zymosan were used to provoke expansion of the Kupffer cell population in rat liver. The number of Kupffer cells per unit of area of liver increased after both stimulations. During these growth phases the number of binding sites for galactose-exposing ligands was studied on Kupffer cell plasma membranes. Both partial hepatectomy and zymosan stimulation affected the binding of lactosylated bovine serum albumin conjugated to gold particles (LacBSA-Au5). The reduction observed depended on the time after the PH or zymosan injection studied. Low levels of binding sites were found at 24 h from PH and 5 days after zymosan stimulation and represented only 1/4 or 1/10 of the binding sites expressed on the cell surface of Kupffer cells from normal adult rats. In addition, in both experimental situations we observed that the clustered distribution of gold particles typical of adult Kupffer cell was changed.

Dormant liver metastases: an experimental study

Experimental work was undertaken to evaluate whether intrahepatic recurrences, observed after resection of colorectal liver metastases in humans, could be due to the activation of dormant cancer cells already present within the liver at liver resection. About 250 cell aggregates (DHDK12 colon carcinoma cell line) were injected into the portal vein of 70 BD IX rats. Eight weeks later, 43 rats with no apparent liver metastases were divided randomly into three groups: group 1 (n = 15) served as control; group 2 (n = 15) were given cyclosporin A (10 mg kg body-weight-1 day-1) for 28 days; and group 3 (n = 13) underwent a 70 per cent hepatectomy. Twelve weeks after the injection of cells, when the animals were killed, 20 per cent of rats in group 1 had liver metastases, 80 per cent in group 2 (P less than 0.01) and 62 per cent in group 3 (P less than 0.05). Undetectable liver micrometastases may have been present at 8 weeks and had not developed until stimulation by cyclosporin A-induced immunosuppression or by liver regeneration after hepatectomy. A similar mechanism may occur clinically and explain some of the recurrences observed after resection of liver metastases.

Cytoreductive surgery impedes metastasis and enhances the immune response: a preliminary report

In an effort to determine the effect of cytoreductive surgery on the metastatic process, MAT-LyLu flank tumors were excised from Copenhagen x Fischer rats and the effects of this surgery on metastatic lung lesions were observed. Cytoreduction resulted in a decrease in lung lesions (P less than 0.05). Adjuvant cyclophosphamide (CTX) further enhanced this beneficial effect. A concurrent increase in the helper/suppressor ratios suggested that this beneficial response might be mediated by the host's immune response.