Intraoperativelym-administered aprotinin and survival after elective liver resection for colorectal cancer metastasis A preliminary study

Methods to decrease blood loss during liver resection: a network meta-analysis

BACKGROUND

Liver resection is a major surgery with significant mortality and morbidity. Specialists have tested various methods in attempts to limit blood loss, transfusion requirements, and morbidity during elective liver resection. These methods include different approaches (anterior versus conventional approach), use of autologous blood donation, cardiopulmonary interventions such as hypoventilation, low central venous pressure, different methods of parenchymal transection, different methods of management of the raw surface of the liver, different methods of vascular occlusion, and different pharmacological interventions. A surgeon typically uses only one of the methods from each of these seven categories. The optimal method to decrease blood loss and transfusion requirements in people undergoing liver resection is unknown.

OBJECTIVES

To assess the effects of different interventions for decreasing blood loss and blood transfusion requirements during elective liver resection.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, and Science Citation Index Expanded to September 2015 to identify randomised clinical trials. We also searched trial registers and handsearched the references lists of identified trials.

SELECTION CRITERIA

We included only randomised clinical trials (irrespective of language, blinding, or publication status) comparing different methods of decreasing blood loss and blood transfusion requirements in people undergoing liver resection.

DATA COLLECTION AND ANALYSIS

Two review authors independently identified trials and collected data. We assessed the risk of bias using Cochrane domains. We conducted a Bayesian network meta-analysis using the Markov chain Monte Carlo method in WinBUGS 1.4, following the guidelines of the National Institute for Health and Care Excellence Decision Support Unit guidance documents. We calculated the odds ratios (OR) with 95% credible intervals (CrI) for the binary outcomes, mean differences (MD) with 95% CrI for continuous outcomes, and rate ratios with 95% CrI for count outcomes, using a fixed-effect model or random-effects model according to model-fit. We assessed the evidence with GRADE.

MAIN RESULTS

We identified 67 randomised clinical trials involving a total of 6197 participants. All the trials were at high risk of bias. A total of 5771 participants from 64 trials provided data for one or more outcomes included in this review. There was no evidence of differences in most of the comparisons, and where there was, these differences were in single trials, mostly of small sample size. We summarise only the evidence that was available in more than one trial below. Of the primary outcomes, the only one with evidence of a difference from more than one trial under the pair-wise comparison was in the number of adverse events (complications), which was higher with radiofrequency dissecting sealer than with the clamp-crush method (rate ratio 1.85, 95% CrI 1.07 to 3.26; 250 participants; 3 studies; very low-quality evidence). Among the secondary outcomes, the only differences we found from more than one trial under the pair-wise comparison were the following: blood transfusion (proportion) was higher in the low central venous pressure group than in the acute normovolemic haemodilution plus low central venous pressure group (OR 3.19, 95% CrI 1.56 to 6.95; 208 participants; 2 studies; low-quality evidence); blood transfusion quantity (red blood cells) was lower in the fibrin sealant group than in the control (MD -0.53 units, 95% CrI -1.00 to -0.07; 122 participants; 2; very low-quality evidence); blood transfusion quantity (fresh frozen plasma) was higher in the oxidised cellulose group than in the fibrin sealant group (MD 0.53 units, 95% CrI 0.36 to 0.71; 80 participants; 2 studies; very low-quality evidence); blood loss (MD -0.34 L, 95% CrI -0.46 to -0.22; 237 participants; 4 studies; very low-quality evidence), total hospital stay (MD -2.42 days, 95% CrI -3.91 to -0.94; 197 participants; 3 studies; very low-quality evidence), and operating time (MD -15.32 minutes, 95% CrI -29.03 to -1.69; 192 participants; 4 studies; very low-quality evidence) were lower with low central venous pressure than with control. For the other comparisons, the evidence for difference was either based on single small trials or there was no evidence of differences. None of the trials reported health-related quality of life or time needed to return to work.

AUTHORS' CONCLUSIONS

Paucity of data meant that we could not assess transitivity assumptions and inconsistency for most analyses. When direct and indirect comparisons were available, network meta-analysis provided additional effect estimates for comparisons where there were no direct comparisons. However, the paucity of data decreases the confidence in the results of the network meta-analysis. Low-quality evidence suggests that liver resection using a radiofrequency dissecting sealer may be associated with more adverse events than with the clamp-crush method. Low-quality evidence also suggests that the proportion of people requiring a blood transfusion is higher with low central venous pressure than with acute normovolemic haemodilution plus low central venous pressure; very low-quality evidence suggests that blood transfusion quantity (red blood cells) was lower with fibrin sealant than control; blood transfusion quantity (fresh frozen plasma) was higher with oxidised cellulose than with fibrin sealant; and blood loss, total hospital stay, and operating time were lower with low central venous pressure than with control. There is no evidence to suggest that using special equipment for liver resection is of any benefit in decreasing the mortality, morbidity, or blood transfusion requirements (very low-quality evidence). Radiofrequency dissecting sealer should not be used outside the clinical trial setting since there is low-quality evidence for increased harm without any evidence of benefits. In addition, it should be noted that the sample size was small and the credible intervals were wide, and we cannot rule out considerable benefit or harm with a specific method of liver resection.

Methods to decrease blood loss during liver resection: a network meta-analysis

BACKGROUND

Liver resection is a major surgery with significant mortality and morbidity. Various methods have been attempted to decrease blood loss and morbidity during elective liver resection. These methods include different methods of vascular occlusion, parenchymal transection, and management of the cut surface of the liver. A surgeon typically uses only one of the methods from each of these three categories. Together, one can consider this combination as a treatment strategy. The optimal treatment strategy for liver resection is unknown.

OBJECTIVES

To assess the comparative benefits and harms of different treatment strategies that aim to decrease blood loss during elective liver resection.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE, and Science Citation Index Expanded to July 2012 to identify randomised clinical trials. We also handsearched the references lists of identified trials.

SELECTION CRITERIA

We included only randomised clinical trials (irrespective of language, blinding, or publication status) where the method of vascular occlusion, parenchymal transection, and management of the cut surface were clearly reported, and where people were randomly assigned to different treatment strategies based on different combinations of the three categories (vascular occlusion, parenchymal transection, cut surface).

DATA COLLECTION AND ANALYSIS

Two review authors identified trials and collected data independently. We assessed the risk of bias using The Cochrane Collaboration's methodology. We conducted a Bayesian network meta-analysis using the Markov chain Monte Carlo method in WinBUGS 1.4 following the guidelines of the National Institute for Health and Care Excellence Decision Support Unit guidance documents. We calculated the odds ratios (OR) with 95% credible intervals (CrI) (which are similar to confidence intervals in the frequentist approach for meta-analysis) for the binary outcomes and mean differences (MD) with 95% CrI for continuous outcomes using a fixed-effect model or random-effects model according to model-fit.

MAIN RESULTS

We identified nine trials with 617 participants that met our inclusion criteria. Interventions in the trials included three different options for vascular occlusion, four for parenchymal transection, and two for management of the cut liver surface. These interventions were combined in different ways in the trials giving 11 different treatment strategies. However, we were only able to include 496 participants randomised to seven different treatment strategies from seven trials in our network meta-analysis, because the treatment strategies from the trials that used fibrin sealant for management of the raw liver surface could not be connected to the network for any outcomes. Thus, the trials included in the network meta-analysis varied only in their approaches to vascular exclusion and parenchymal transection and none used fibrin sealant. All the trials were of high risk of bias and the quality of evidence was very low for all the outcomes. The differences in mortality between the different strategies was imprecise (seven trials; seven treatment strategies; 496 participants). Five trials (six strategies; 406 participants) reported serious adverse events. There was an increase in the proportion of people with serious adverse events when surgery was performed using radiofrequency dissecting sealer compared with the standard clamp-crush method in the absence of vascular occlusion and fibrin sealant. The OR for the difference in proportion was 7.13 (95% CrI 1.77 to 28.65; 15/49 (adjusted proportion 24.9%) in radiofrequency dissecting sealer group compared with 6/89 (6.7%) in the clamp-crush method). The differences in serious adverse events between the other groups were imprecise. There was a high probability that 'no vascular occlusion with clamp-crush method and no fibrin' and 'intermittent vascular occlusion with Cavitron ultrasonic surgical aspirator and no fibrin' are better than other treatments with regards to serious adverse events. Quality of life was not reported in any of the trials.The differences in the proportion of people requiring blood transfusion was imprecise (six trials; seven treatments; 446 participants). Two trials (three treatments; 155 participants) provided data for quantity of blood transfused. People undergoing liver resection by intermittent vascular occlusion had higher amounts of blood transfused than people with continuous vascular occlusion when the parenchymal transection was carried out with the clamp-crush method and no fibrin sealant was used for the cut surface (MD 1.2 units; 95% CrI 0.08 to 2.32). The differences in the other comparisons were imprecise (very low quality evidence). Three trials (four treatments; 281 participants) provided data for operative blood loss. People undergoing liver resection using continuous vascular occlusion had lower blood loss than people with no vascular occlusion when the parenchymal transection was carried out with clamp-crush method and no fibrin sealant was used for the cut surface (MD -130.9 mL; 95% CrI -255.9 to -5.9). None of the trials reported the proportion of people with major blood loss.The differences in the length of hospital stay (six trials; seven treatments; 446 participants) and intensive therapy unit stay (four trials; six treatments; 261 participants) were imprecise. Four trials (four treatments; 245 participants) provided data for operating time. Liver resection by intermittent vascular occlusion took longer than liver resection performed with no vascular occlusion when the parenchymal transection was carried out with Cavitron ultrasonic surgical aspirator and no fibrin sealant was used for the cut surface (MD 49.6 minutes; 95% CrI 29.8 to 69.4). The differences in the operating time between the other comparisons were imprecise. None of the trials reported the time needed to return to work.

AUTHORS' CONCLUSIONS

Very low quality evidence suggested that liver resection using a radiofrequency dissecting sealer without vascular occlusion or fibrin sealant may increase serious adverse events and this should be evaluated in further randomised clinical trials. The risk of serious adverse events with liver resection using no special equipment compared with more complex methods requiring special equipment was uncertain due to the very low quality of the evidence. The credible intervals were wide and considerable benefit or harm with a specific method of liver resection cannot be ruled out.

Pharmacological interventions to decrease blood loss and blood transfusion requirements for liver resection

BACKGROUND

Blood loss during liver resection is one of the most important factors affecting the peri-operative outcomes of patients undergoing liver resection.

OBJECTIVES

To determine the benefits and harms of pharmacological interventions to decrease blood loss and to decrease allogeneic blood transfusion requirements in patients undergoing liver resections.

SEARCH STRATEGY

We searched The Cochrane Hepato-Biliary Group Controlled Trials Register, the Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library, MEDLINE, EMBASE, and Science Citation Index Expanded until November 2008 for identifying the randomised trials.

SELECTION CRITERIA

We included all randomised clinical trials comparing various pharmacological interventions aimed at decreasing blood loss and allogeneic blood transfusion requirements in liver resection. Trials were included irrespective of whether they included major or minor liver resections, normal or cirrhotic livers, vascular occlusion was used or not, and irrespective of the reason for liver resection.

DATA COLLECTION AND ANALYSIS

Two authors independently identified trials for inclusion and independently extracted data. We analysed the data with both the fixed-effect and the random-effects models using RevMan Analysis. For each outcome we calculated the risk ratio (RR), mean difference (MD), or standardised mean difference with 95% confidence intervals (CI) based on intention-to-treat analysis or available case-analysis. For dichotomous outcomes with only one trial included under the outcome, we performed the Fisher's exact test.

MAIN RESULTS

Six trials involving 849 patients satisfied the inclusion criteria. Pharmacological interventions included aprotinin, desmopressin, recombinant factor VIIa, antithrombin III, and tranexamic acid. One or two trials could be included under most comparisons. All trials had a high risk of bias. There was no significant difference in the peri-operative mortality, survival at maximal follow-up, liver failure, or other peri-operative morbidity. The risk ratio of requiring allogeneic blood transfusion was significantly lower in the aprotinin and tranexamic acid groups than the respective control groups. Other interventions did not show significant decreases of allogeneic transfusion requirements.

AUTHORS' CONCLUSIONS

None of the interventions seem to decrease peri-operative morbidity or offer any long-term survival benefit. Aprotinin and tranexamic acid show promise in the reduction of blood transfusion requirements in liver resection surgery. However, there is a high risk of type I (erroneously concluding that an intervention is beneficial when it is actually not beneficial) and type II errors (erroneously concluding that an intervention is not beneficial when it is actually beneficial) because of the few trials included, the small sample size in each trial, and the high risk of bias. Further randomised clinical trials with low risk of bias and random errors assessing clinically important outcomes such as peri-operative mortality are necessary to assess any pharmacological interventions aimed at decreasing blood loss and blood transfusion requirements in liver resections. Trials need to be designed to assess the effect of a combination of different interventions in liver resections.

A possible association between aprotinin and improved survival after radical surgery for mesothelioma

BACKGROUND

Aprotinin has been used to decrease blood loss with complicated cardiac surgery but has not been investigated in extrapleural pneumonectomy, an operation that does not use cardiopulmonary bypass. In this prospective, randomized, placebo-controlled, double-blind trial, the authors investigated whether aprotinin decreased blood loss in patients who underwent this operation.

METHODS

After appropriate statistical design and institutional review board approval, eligible patients who were scheduled for extrapleural pneumonectomy were randomized to receive either aprotinin or placebo during the operation. Blood loss and survival data were obtained from electronic medical records and surgical databases.

RESULTS

Of 20 patients who were enrolled, 16 patients met criteria for blood loss analysis. Four patients were excluded from the blood loss analysis: Three patients were inoperable because of tumor spread and underwent limited surgery, and 1 patient died intraoperatively because of acute, massive hemorrhage. The mean blood loss was 769 mL with aprotinin versus 1832 mL with placebo (P = .05; Wilcoxon test). All 20 patients were included in survival analyses. All 9 patients who received placebo died. In contrast, 7 of 11 patients who received aprotinin remained alive at the time of the current report. Kaplan-Meier survival curves differed significantly between the 2 groups (P = .0004). A Bayesian multivariate survival analysis of 18 patients who had complete data available on 8 prognostic variables indicated a posterior probability of .99 that aprotinin was beneficial.

CONCLUSIONS

Aprotinin decreased blood loss. After accounting for covariate effects, there was a significant comparative benefit with aprotinin in postoperative survival. This finding was unexpected and could not be considered conclusive because of the small size of the current study. A confirmatory study may be warranted.

Hypercoagulability and lung cancer

The relationship between cancer and coagulopathy was suggested by Trousseau nearly 150 years ago. Later, it became more evident that oncologic patients are at a higher risk of experiencing thromboembolic events. This can be due to activation of the coagulation system either by neoplastic cells or by prescribed therapies (chemotherapy or surgical procedures). In fact, these events can constitute the first manifestation of cancer, and their recurrence, despite efficient anticoagulation, has been described. The coagulation system is normally activated in order to provide healing. In the presence of neoplasms, this complex system is activated as a response to multiple stimuli and seems to contribute to cancer progression. Activation of the coagulation system has a greater effect on metastatic foci than on the primary tumor. However, most cancer victims die from complications caused by metastasis, which underscores the importance of this theme. In this area, various mechanisms have been described, creating promising perspectives for future treatments. The current success in using low-molecular-weight heparins against small cell lung cancer is encouraging. Although the knowledge of those mechanisms is relatively incipient, many basic research and clinical studies are underway.

The coagulation system as a target for experimental therapy of human gliomas

The purpose of this paper is to review the rationale for the development of coagulation-reactive drugs for the experimental therapy of gliomas. Numerous reactants familiar to students of blood coagulation have been shown to contribute to neoplastic proliferation, invasion and metastasis. Recently, considerable progress has been made in demonstrating the ability of drugs capable of inhibiting these reactants to alter cancer progression. Biological features of gliomas within the realm of blood coagulation suggest that clinical trials of such drugs warrant consideration. This approach offers the prospect of a novel treatment for this devastating tumour type that does not share the toxicities of conventional cancer therapies.

Anticoagulants in cancer treatment: malignancy as a solid phase coagulopathy

The purpose of this review is to demonstrate the potential for development of coagulation-reactive drugs for experimental cancer treatment. Improved cancer outcome has been reported in several tumor types with drugs that interfere with thrombin-generating or urokinase-initiated pathways expressed by tumor cells. These pathways participate in the response to injury and their inappropriate expression by malignant cells supports tumor growth. A proposed classification of tumor types based on the differential occurrence of these pathways may account for variation in drug responsiveness and guide clinical trial design. Among drugs available for testing, aprotinin and low molecular weight heparin have particular appeal. The former blocks a pathway of tumor cell growth, invasion and metastasis while the latter blocks growth factor activity, angiogenesis, and other tumor growth mechanisms as well as coagulation activation. Conceiving of malignancy as a solid phase coagulopathy may facilitate development of effective but non-toxic cancer treatments and encourage inquiry into the putative 'injury' responsible for both coagulation activation and carcinogenesis.

Cancer treatment with inhibitors of urokinase-type plasminogen activator and plasmin

The urokinase-type plasminogen activator-plasmin system plays an important role in many normal physiological processes including clot lysis, wound healing, embryogenesis and tissue remodelling. It is also involved in the pathogenesis of human malignancy through its ability to mediate tumour cell growth, invasion and metastatic dissemination. Interfering with this system is an appealing approach for experimental therapy of malignancy for several reasons. This concept is supported by a wealth of preclinical data. Evidence exists suggesting a role for this system in several major human tumour types. Preliminary evidence suggests that agents which block this pathway are effective in therapeutic doses that are already defined and relatively non-toxic. This form of treatment is not likely to carry cross-resistance with other types of cancer therapy and should be applicable to both localised and advanced tumours. Since heterogeneity in responsiveness among various tumour types is expected, clinical effects in given tumours would provide a basis for interpreting mechanisms of tumour progression in vivo and for future development of drugs with improved efficacy. Inhibition of the urokinase-type plasminogen activator-plasmin system remains a promising, but largely untested, area of experimental cancer therapeutics.