Surgery (Austin & Northern Health) - Research Publications
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ItemInduction of Th1Immune responses following laser ablation in a murine model of colorectal liver metastases(BIOMED CENTRAL LTD, 2011-05-29)BACKGROUND: Preliminary experimental studies have suggested that the in situ destruction of tumor tissue by local laser ablation (LA) may also stimulate host immunity against cancer. We investigated local and systemic induction of immune responses after laser ablation in the setting of residual tumor. METHODS: A murine colorectal cancer (CRC) liver metastasis model was used. Selected tumors of liver CRC bearing mice and livers of mice without tumor induction were treated with LA. Liver and tumor tissues from the ablation sites and from distant sites were collected at various time points following LA and changes in CD3+ T cells and Kupffer cells (F4/80 marker) infiltration and the expression of interferon gamma (IFNγ) were investigated by immunohistochemistry and ELISpot. Base line levels of CD3+ T cells and Kupffer cells were established in untreated mice. RESULTS: The presence of tumor induced significant accumulation of CD3+ T cells and Kupffer cells at the tumor-host interface, within the tumor vascular lakes and increased their baseline concentration within the liver parenchyma. LA of the liver induced accumulation of CD3+ T-cells and Kupffer cells at the site of injury and systemic induction of immune responses as discerned by the presence of IFNγ secreting splenocytes. LA of liver tumors induced significant increase of CD3+ T-cells at site of injury, within normal liver parenchyma, and the tumor-host interface of both ablated and distant tumors. In contrast Kupffer cells only accumulated in ablated tumors and the liver parenchyma but not in distant tumors. IFNγ expression increased significantly in ablated tumors and showed an increasing trend in distant tumors. CONCLUSION: Laser ablation in addition to local tumor destruction induces local and systemic Th1 type immune responses which may play a significant role in inhibiting tumor recurrence from residual micrometastases or circulating tumor cells.
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ItemThe prognostic significance of lymphatics in colorectal liver metastases.(Hindawi Limited, 2014)Background. Colorectal Cancer (CRC) is the most common form of cancer diagnosed in Australia across both genders. Approximately, 40%-60% of patients with CRC develop metastasis, the liver being the most common site. Almost 70% of CRC mortality can be attributed to the development of liver metastasis. This study examines the pattern and density of lymphatics in colorectal liver metastases (CLM) as predictors of survival following hepatic resection for CLM. Methods. Patient tissue samples were obtained from the Victorian Cancer Biobank. Immunohistochemistry was used to examine the spatial differences in blood and lymphatic vessel densities between different regions within the tumor (CLM) and surrounding host tissue. Lymphatic vessel density (LVD) was assessed as a potential prognostic marker. Results. Patients with low lymphatic vessel density in the tumor centre, tumor periphery, and adjacent normal liver demonstrated a significant disease-free survival advantage compared to patients with high lymphatic vessel density (P = 0.01, P > 0.01, and P = 0.05, resp.). Lymphatic vessel density in the tumor centre and periphery and adjacent normal liver was an accurate predictive marker of disease-free survival (P = 0.05). Conclusion. Lymphatic vessel density in CLM appears to be an accurate predictor of recurrence and disease-free survival.
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ItemTreatment with the vascular disruptive agent OXi4503 induces an immediate and widespread epithelial to mesenchymal transition in the surviving tumor(WILEY-BLACKWELL, 2013-10)Epithelial to mesenchymal transition (EMT) is considered an important mechanism in tumor resistance to drug treatments; however, in vivo observation of this process has been limited. In this study we demonstrated an immediate and widespread EMT involving all surviving tumor cells following treatment of a mouse model of colorectal liver metastases with the vascular disruptive agent OXi4503. EMT was characterized by significant downregulation of E-cadherin, relocation and nuclear accumulation of β-catenin as well as significant upregulation of ZEB1 and vimentin. Concomitantly, significant temporal upregulation in hypoxia and the pro-angiogenic growth factors hypoxia-inducible factor 1-alpha, hepatocyte growth factor, vascular endothelial growth factor and transforming growth factor-beta were seen within the surviving tumor. The process of EMT was transient and by 5 days after treatment tumor cell reversion to epithelial morphology was evident. This reversal, termed mesenchymal to epithelial transition (MET) is a process implicated in the development of new metastases but has not been observed in vivo histologically. Similar EMT changes were observed in response to other antitumor treatments including chemotherapy, thermal ablation, and antiangiogenic treatments in our mouse colorectal metastasis model and in a murine orthotopic breast cancer model after OXi4503 treatment. These results suggest that EMT may be an early mechanism adopted by tumors in response to injury and hypoxic stress, such that inhibition of EMT in combination with other therapies could play a significant role in future cancer therapy.
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ItemBiliary stenting versus surgical bypass for palliation of periampullary malignancy(SPRINGER INDIA, 2013-03)BACKGROUND: Patients with periampullary cancers may not be suitable for curative resection due to locally advanced disease, metastases, or poor health. Biliary stenting and surgical bypass are utilized for symptom control, but the true benefit of one technique over the other is not clear. METHODS: A retrospective analysis of case records was undertaken of patients with periampullary (pancreatic head/uncinate process, distal bile duct, and ampulla of Vater and surrounding duodenum) malignancy treated between June 2004 and June 2010 in a tertiary center by palliative biliary stenting or palliative surgical bypass. RESULTS: Of the 69 patients included in the analysis, combined biliary and gastric bypass was performed on 28, while 41 underwent biliary stent (metallic, n = 39) insertion. Patients undergoing stenting were significantly older and less likely to be offered chemotherapy than those from the surgical bypass group. Overall, there were significantly more complications in the stent insertion group (85 %) than the surgical bypass group (36 %) (p = 0.003). The stent group required significantly more subsequent procedures than the surgical bypass group. Metal stent obstruction occurred in 16 of 39 (41 %) patients, with a median stent patency of 224 days. The overall median survival of patients in this study was 7 months with no significant difference between the groups (p = 0.992). The presence of metastases at presentation was the only independent factor associated with decreased survival. CONCLUSION: There was no survival difference between stenting vs. surgical bypass for palliation of periampullary cancer. There was, however, a high rate of stent occlusion and need for repeat procedures in patients treated by metal stenting, suggesting that stenting may be best suited to patients predicted as having the shortest survival.
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ItemPressurized Pulse Irrigation with Saline Reduces Surgical-site Infections following Major Hepatobiliary and Pancreatic Surgery: Randomized Controlled Trial(SPRINGER, 2014-02)BACKGROUND: Surgical site infections (SSI) are a significant cause of postoperative morbidity. Pressurized pulse irrigation of subcutaneous tissues may lower infection rates by aiding in the debridement of necrotic tissue and reducing bacterial counts compared to simply pouring saline into the wound. METHODS: A total of 128 patients undergoing laparotomy extending beyond 2 h were randomized to treatment of wounds by pressurized pulse lavage irrigation (<15 psi) with 2 L normal saline (pulse irrigation group), or to standard irrigation with 2 L normal saline poured into the wound, immediately prior to skin closure (standard group). Only elective cases were included, and all cases were performed within a specialized hepatobiliary and pancreatic surgery unit. RESULTS: There were 62 patients managed by standard irrigation and 68 were managed by pulse irrigation. The groups were comparable in most aspects. Overall there were 16 (13 %) SSI. Significantly fewer SSI occurred in the pulse irrigation group [4 (6 %) vs. 12 (19 %); p = 0.032]. On multivariate analysis, the use of pulse irrigation was the only factor associated with a reduction in SSI with an odds ratio (OR) of 0.3 [95 % confidence interval (95 % CI) 0.1-0.8; p = 0.031]. In contrast, hospital length of stay of greater than 14 days was associated with increased infections with an OR of 7.6 (95 % CI 2.4-24.9; p = 0.001). CONCLUSIONS: Pulse irrigation of laparotomy wounds in operations exceeding 2 h duration reduced SSI after major hepatobiliary pancreatic surgery. (Australian New Zealand Clinical Trials Registry, ACTRN12612000170820).
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ItemBlockade of the renin-angiotensin system inhibits growth of colorectal cancer liver metastases in the regenerating liver(SPRINGER, 2014-04)Partial hepatectomy (PH), the preferred option for selected patients with colorectal cancer liver metastases (CRCLM), is associated with 40-80% tumor recurrence rates. Renin-angiotensin system (RAS) blockade inhibits tumor growth and has been suggested to improve liver regeneration. We documented the effect of RAS blockade on tumor growth and liver regeneration in a murine model. CRCLM induction followed by 70% PH was performed on 78 CBA mice. Liver regeneration (days 2, 6) and CRCLM tumor load were measured by liver (and tumor) weights, percentage of CRCLM burden and tumor nodule count (days 16, 21). mRNA expression of the RAS components was characterised. Statistical analysis was performed using 2-independent sample T test or Mann-Whitney test (SPSS). Captopril did not impair liver regeneration. By day 21, Captopril decreased tumor burden (percentage of CRCLM in the liver) (48.7 ± 4.7% control, 24.4 ± 6.2 Captopril; p = 0.008), tumor volume (1046.2 ± 200.2 mm(3), 388.3 ± 150.4; p = 0.02), tumor nodule count per image field (181.1 ± 28.5, 68 ± 17.6; p = 0.005) and tumor angiogenesis (71.8 ± 6.4 vessels/mm(2), 43.1 ± 7.6; p = 0.015) compared to controls. Captopril enhanced tumor apoptosis (1 ± 0.2%, 2.5 ± 0.7; p = 0.028). Liver regeneration and tumor development increased liver ACE levels. Blockade of the RAS effectively retarded CRCLM tumor growth at the late stage of tumor development within the regenerating liver without impeding liver regeneration following PH, via anti-angiogenesis and pro-tumor apoptosis. Captopril may be of therapeutic benefit in patients undergoing PH for CRCLM.
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ItemSpatial morphological and molecular differences within solid tumors may contribute to the failure of vascular disruptive agent treatments(BIOMED CENTRAL LTD, 2012-11-15)BACKGROUND: Treatment of solid tumors with vascular disrupting agent OXi4503 results in over 90% tumor destruction. However, a thin rim of viable cells persists in the tumor periphery following treatment, contributing to subsequent recurrence. This study investigates inherent differences in the microenvironment of the tumor periphery that contribute to treatment resistance. METHODS: Using a murine colorectal liver metastases model, spatial morphological and molecular differences within the periphery and the center of the tumor that may account for differences in resistance to OXi4503 treatment were investigated. H&E staining and immunostaining were used to examine vessel maturity and stability, hypoxia and HIF1α levels, accumulation of immune cells, expression of proangiogenic factors/receptors (VEGF, TGF-β, b-FGF, and AT1R) and expression of EMT markers (ZEB1, vimentin, E-cadherin and β-catenin) in the periphery and center of established tumors. The effects of OXi4503 on tumor vessels and cell kinetics were also investigated. RESULTS: Significant differences were found between tumor periphery and central regions, including association of the periphery with mature vessels, higher accumulation of immune cells, increased growth factor expression, minimal levels of hypoxia and increased evidence of EMT. OXi4503 treatment resulted in collapse of vessels in the tumor center; however vasculature in the periphery remained patent. Similarly, tumor apoptosis and proliferation were differentially modulated between centre and periphery after treatment. CONCLUSIONS: The molecular and morphological differences between tumor periphery and center may account for the observed differential resistance to OXi4503 treatment and could provide targets for drug development to totally eliminate metastases.
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ItemNo Preview AvailableOutcomes of contemporary management of gangrenous and non-gangrenous acute cholecystitis(WILEY-BLACKWELL, 2011-08)BACKGROUND: Gangrenous cholecystitis (GC) is considered a more severe form of acute cholecystitis. The risk factors associated with this condition and its impact on morbidity and mortality compared with those of non-gangrenous acute cholecystitis (NGAC) are poorly defined and based largely on findings from older studies. METHODS: Patients with histologically confirmed acute cholecystitis treated in specialized units in a tertiary hospital between 2005 and 2010 were identified from a prospectively maintained database. Data were reviewed retrospectively and patients with GC were compared with those with NGAC. RESULTS: A total of 184 patients with NGAC and 106 with GC were identified. The risk factors associated with GC included older age (69 years vs. 57 years; P= 0.001), diabetes (19% vs. 10%; P= 0.049), temperature of >38 °C (36% vs. 16%; P < 0.001), tachycardia (31% vs. 15%; P= 0.002), detection of muscle rigidity on examination (27% vs. 12%; P= 0.01) and greater elevations in white cell count (WCC) (13.4 × 10⁹/l vs. 10.7 × 10⁹/l; P < 0.001), C-reactive protein (CRP) (94 mg/l vs. 17 mg/l; P= 0.001), bilirubin (19 µmol/l vs. 17 µmol/l; P= 0.029), urea (5.3 mmol/l vs. 4.7 mmol/l; P= 0.016) and creatinine (82 µmol/l vs. 74 µmol/l; P= 0.001). The time from admission to operation in days was greater in the GC group (median = 1 day, range: 0-14 days vs. median = 1 day, range: 0-10 days; P= 0.029). There was no overall difference in complication rates between the GC and NGAC groups (22% vs. 14%; P= 0.102). There was a lower incidence of common bile duct stones in the GC group (5% vs. 13%; P= 0.017). Gangrenous cholecystitis was associated with increased mortality (4% vs. 0%; P= 0.017), but this was not an independent risk factor on multivariate analysis. CONCLUSIONS: Gangrenous cholecystitis has certain clinical features and associated laboratory findings that may help to differentiate it from NGAC. It is not associated with an overall increase in complications when treated in a specialized unit.