Chemotherapy enhances endothelial cell reactivity to platelets

Hypercoagulability State Combined with Post-Treatment Hypofibrinolysis in Invasive Breast Cancer: A Seven-Year Follow-Up Evaluating Disease-Free and Overall Survival

(1) Background: Cancer treatment, including chemotherapy, endocrine therapy, targeted therapy and radiotherapy, has been identified as an important independent risk factor for venous thromboembolism in cancer patients. The aim of the study was to evaluate the effect of adjuvant therapy on the coagulation and fibrinolysis components in invasive breast cancer. (2) Methods: Tissue factor pathway inhibitor (TFPI), tissue factor (TF), tissue plasminogen activator (t-PA), plasminogen activator inhibitor-1 (PAI-1) antigen (concentration) and TFPI and TF activities were examined in the blood samples of 60 breast cancer patients treated by adjuvant chemotherapy, endocrine therapy, radiotherapy and immunotherapy. Blood samples were taken 24 h before primary surgery and 8 months after tumour removal surgery. (3) Results: Adjuvant therapy administrated to breast cancer patients significantly increased the concentration of plasma TF, the PAI-1 antigen and also the activity of TFPI and TF, but significantly decreased the level of the t-PA antigen. Combined chemotherapy and endocrine therapy, but not monotherapy, has an important effect on haemostatic biomarker levels. (4) Conclusions: Breast cancer patients receiving adjuvant therapy have an elevated risk of developing a hypercoagulability and hypofibrinolysis state leading to venous thromboembolism.

Safety and Quality of Life in Women with Immediate Reconstruction with Polyurethane Implants after Neoadjuvant Chemotherapy: Outcomes from The Preq-20 Trial

INTRODUCTION

Various studies have evaluated the impact of neoadjuvant chemotherapy (NAC) on the complications of breast cancer surgery, most of which were retrospective and did not assess the variables related to postoperative risk factors. The aim of this study is to analyse the safety and satisfaction of women included in the PreQ-20 trial who underwent NAC and who underwent mastectomy and immediate reconstruction with prepectoral polyurethane implants.

MATERIAL AND METHODS

The patients included in the study belong to the prospective study PreQ-20. The study group consisted of patients who underwent immediate reconstruction after primary systemic therapy. The control groups consisted of patients with immediate reconstruction and adjuvant chemotherapy (control group 1) and patients with an infiltrating carcinoma or in situ ductal carcinoma who did not require chemotherapy (control group 2).

RESULTS

The study included 157 women, 58 (36.9%) of whom underwent primary systemic therapy. The indication for genetic study was significantly greater for the study group (87.9%) than for control groups 1 (49.1%) or 2 (30.4%). Seventy-two (45.9%) of the patients underwent bilateral mastectomy (BM), a procedure that was performed significantly more frequently in the study group (69%) than in control groups 1 (30.2%) or 2 (34.8%). The incidence rate for BM after complete pathologic response was 78%. There were no statistically significant differences in the number of complications between the groups. Implant loss was significantly more frequent in control group 1 (13.2%) than in the study group (3.4%) and control group 2 (2.2%).

CONCLUSIONS

Mastectomy with prepectoral polyurethane implant reconstruction in patients with neoadjuvant chemotherapy presented a similar incidence of complications compared with patients who underwent primary surgery. There is a high rate of BM in women with NAC.

The impact of neoadjuvant systemic treatment on postoperative complications in breast cancer surgery

PURPOSE

The aim of the study was to analyze the impact of neoadjuvant systemic treatment (NST) on postoperative complications and the beginning of adjuvant treatment.

METHODS

This study includes data from a prospectively maintained database including patients with breast cancer (BC) stage I-IV with or without NST undergoing breast cancer surgery between January 2010 and September 2021.

RESULTS

Out of 517 enrolled patients, 77 received NST, 440 had primary breast surgery. After NST patients underwent surgery after a meantime of 34 days (26.5-40 days). No statistical significance could be found comparing the complication grading according to the Clavien Dindo classification. The complications were most frequently rated as grade 3b. There were no complications with grade 4 or higher. When differentiating into short and long-term, the overall rate of short-term complications was 20.3% with no significant difference between the two groups (20.8% vs. 20.2%). Regarding long-term complications, there was more impairment of shoulder mobility (26.0% vs. 9.5%, p ≤ 0.001) and chronic pain (42.9% vs. 28.6%, p ≤ 0.016) for patients with NST. The beginning of the administration of the adjuvant treatment was comparable in both groups (46.3 days vs. 50.5 days).

CONCLUSION

In our cohort, complications between both groups were comparable according to Clavien Dindo. This study shows that NST has no negative impact on postoperative short-term complications and most importantly did not lead to a delay of the beginning of adjuvant treatment. Therefore, NST can be safely admitted, even when followed by extensive breast reconstruction surgery.

Impact of neoadjuvant chemotherapy on surgical complications in breast cancer: A systematic review and meta-analysis

BACKGROUND

The increased use of neoadjuvant chemotherapy (NACT) facilitates an increase in breast-conserving surgery and immediate breast reconstruction. While NACT is considered to have the same oncological safety as adjuvant chemotherapy, evidence on the impact of NACT on surgical outcomes following breast surgery is unclear and varies across studies. The aim of this systematic review and meta-analysis was to assess the impact of NACT on surgical complications in breast cancer patients undergoing any kind of breast surgery.

METHODS

Database searches were conducted (March 26, 2021) to identify studies assessing the impact of NACT on postoperative complications. Studies were included if they compared a group of patients treated with NACT to a control group that was not, and if they reported at least one of our defined outcomes. Primary effect measures were odds ratios (ORs) and mean difference with a 95% confidence interval. Study quality was assessed by the Newcastle-Ottawa Scale.

RESULTS

Twenty-six studies comprising 134,191 patients were included. NACT was not associated with an increased complication rate for overall complications (OR: 1.13, 95% CI: 0.86 to 1.47, p = 0.38), individual postoperative complications, nor surgery duration. There was a non-significant trend towards NACT increasing the risk of seroma, wound complications, skin or nipple necrosis, flap ischemia or loss, and implant loss. A significant difference in blood loss was found, favouring NACT (MD = -75.85, 95% CI: -107.47 to -44.23, p < 0.00001). Heterogeneity was significant between the studies (I²>50%).

CONCLUSION

Compared to a control group, NACT was not found to affect the surgical complications adversely.

An overview of thrombotic complications of old and new anticancer drugs

Thrombosis is a common complication of cancer with a mean prevalence of 15%. Most commonly, this presents as venous thromboembolism; however, other manifestations such as arterial thrombosis or thrombotic microangiopathy may occur. Cancer itself is not only associated with risk factors for thrombotic complications, including intrinsic biological effect of malignant cells, accompanying operations, or the presence of indwellingvascular catheters, but there is also an additional risk caused by anticancer agents including chemotherapy and immunotherapy. In most cases the underlying pathogenetic factor that contributes to the thrombotic risk associated with chemotherapy is endothelial cell injury (or loss of protection of endothelial integrity, for example by vascular endothelial growth factor inhibition). In addition, individual anticancer agents may have specific prothrombotic effects. As in recent years more intense anticancer drugs are administered, such as in myeloablative conditioning regimens preceding stem cell transplantation, thrombosis and in particular thrombotic microangiopathy are a more frequent complication in anticancer treatment.

Pathophysiology of Coagulopathy in Hematological Malignancies and in COVID-19

Many severe illnesses with a systemic impact may cause activation of coagulation. While systemic activation of coagulation leads to a coagulopathy that follows many common activation pathways and failure of endogenous regulatory anticoagulant systems, underlying conditions may utilize distinctive pathogenetic routes and may vary in clinical manifestations of the coagulopathy. The coagulation derangement associated with hematological malignancies and the coagulopathy of coronavirus disease 2019 (COVID-19) clearly demonstrate such differences. Malignancies are associated with venous thromboembolism due to the biological effect of malignant cells, frequent medical interventions, or the presence of indwelling vascular catheters. The underlying pathogenesis of cancer-associated coagulopathy relies on tissue factor-mediated activation of coagulation, cytokine-controlled defective anticoagulant pathways, fibrinolytic changes, and dysfunctional endothelium. There is an additional risk caused by anti-cancer agents including chemotherapy and immunotherapy. The underlying pathogenetic factor that contributes to the thrombotic risk associated with chemotherapy is endothelial cell injury (or loss of protection of endothelial integrity, for example, by vascular endothelial growth factor inhibition). In addition, individual anti-cancer agents may have specific prothrombotic effects. One of the remarkable features of severe COVID-19 infections is a coagulopathy that mimics but is not identical to the disseminated intravascular coagulation and thrombotic microangiopathy and has been identified as a strong marker for an adverse outcome. Severe COVID-19 infections cause inflammation-induced changes in coagulation in combination with severe endothelial cell injury. This coagulopathy likely contributes to pulmonary microvascular thrombosis, bronchoalveolar fibrin deposition (which is a hallmark of acute respiratory distress syndrome) and venous thromboembolic complications.

Cancer and thrombosis: new insights to an old problem

Venous thromboembolism (VTE) is a common complication in patients with cancer and portends a poor prognosis. Our understanding of the underlying pathophysiology of VTE in cancer has advanced since Trousseau first described hypercoagulability in patients with malignancy and Virchow described his famous triad of thrombosis formation. Malignancy itself induces a thrombophilic state by increasing the risk of venous stasis, endothelial injury and an imbalance of pro and anti-thrombotic factors leading to a hypercoaguable state. Additional insults to this thrombotic balance are introduced by patient-specific, treatment related and tumor-specific factors. The importance of understanding the factors associated with increased thrombosis in cancer is paramount in order to adequately identify patients who will benefit from thromboprophylaxis.

Hematological Malignancies and Arterial Thromboembolism

Established guidelines exist for prevention and treatment of venous thromboembolism in hematological malignancies, but none for arterial thromboembolism. However, arterial and venous thromboembolism share the same provoking features—including altered procoagulant factors and defective fibrinolytic system. The morbidity for arterial thromboembolism is increasing in hematological malignancies, with the advent of immunomodulatory and targeted therapy. However, survival rate for hematological malignancy is improving. Consequently, as patients with hematological malignancies live longer, comorbidities including diabetes, hypertension and dyslipidemia, may accentuate arterial thrombosis. Thus far, the scientific literature on prophylaxis and treatment for arterial thromboembolism in hematological malignancies is limited. This review highlights the pathogenesis, incidence and clinical features of arterial thromboembolism in hematological malignancies.

Venous Thromboembolism and Malignant Brain Tumors: A Review

The incidence of venous thromboembolism (VTE) in patients with primary brain tumors varies be tween 1 and 60%. This variability in incidence is due to study differences in (a) methods of diagnosis of VTE— i.e., diagnosis at autopsy or clinical diagnosis; (b) amount of time from surgery to VTE diagnosis; (c) proportion of patients receiving deep venous thrombosis (DVT) pro phylaxis ; (d) clinical risk factors associated with VTE, such as paresis, prior thrombotic disease, and chemother apy; and (e) tumor location and histology. The etiology of VTE in patients with primary brain tumors is unknown. The preoperative hemostatic abnormalities noted in clin ical studies have been most consistent with compensated disseminated intravascular coagulation (DIC). These ab normalities, however, appear to be of little predictive value for the subsequent development of VTE. Studies involving brain tumor tissue or cell cultures have impli cated factors released by the tumor or surrounding neural tissue that activate the coagulation system or inhibit fi brinolysis. Recommendations for VTE prophylaxis in clude (a) earliest possible ambulation; (b) intermittent pneumatic compression in all nonambulatory patients preoperatively and postoperatively; and (c) s.c. heparin in high-risk patients. The role of low-molecular-weight heparin in VTE prophylaxis has not been established. Patients with malignant brain tumors can be safely anti coagulated with heparin and warfarin if these agents are carefully monitored. Of 197 patients in seven series who received anticoagulants, only 5 (2.5%) had intracranial bleeding. Vena caval filters and thrombectomy are rarely required. Thrombolytic therapy is contraindicated. Key Words: Venous thromboembolism—Deep venous throm bosis—Malignant brain tumors.

A rare cause of chest pain in a cancer patient

It is well known that cancer and hypercoagulability go hand in hand. Most thromboembolism is venous in nature although arterial thrombosis can occur. Arterial thrombosis secondary to malignancy is usually seen in the lower extremities; however, it can also be seen elsewhere. This is a case of bronchogenic carcinoma with no history of typical atherosclerotic risk factors including smoking, diabetes mellitus, hypertension, or hyperlipidemia presented with chest pain and was found to have an acute ST segment elevation myocardial infection. Coronary angiography showed a large thrombus in the left anterior descending artery in the absence of any atherosclerotic lesions. Malignancy is considered to be the major contributing factor for this myocardial infarction in the absence of both atherosclerotic risk factors and atherosclerotic lesions in the coronary angiography. We will focus on the relationship between cancer and thrombosis with special emphasis on arterial thromboembolism with subsequent development of myocardial infarction.

Investigation of Proposed Mechanisms of Chemotherapy-Induced Venous Thromboembolism

Venous thromboembolism (VTE) during chemotherapy is common, with 7% mortality in metastatic breast cancer (MBC). In a prospective cohort study of patients with breast cancer, we investigated whether vascular endothelial cell activation (VECA), and whether apoptosis, is the cause of chemotherapy-induced VTE. Methods: Serum markers of VECA, E-selectin (E-sel), vascular cell adhesion molecule 1 (VCAM-1) and d-dimer (fibrin degradation and hypercoagulability marker) were measured prechemotherapy and at 1, 4, and 8 days following chemotherapy. Clinical deep vein thrombosis (DVT) or pulmonary embolism and occult DVT detected by duplex ultrasound imaging were recorded as VTE-positive (VTE+). In patients with MBC, hypercoagulable response to chemotherapy was compared between patients with and without cancer progression. Development of VTE and cancer progression was assessed 3 months following starting chemotherapy. Results: Of the 134 patients, 10 (7.5%) developed VTE (6 [17%] of 36 MBC receiving palliation, 0 of 11 receiving neoadjuvant to downsize tumor, and 4 [5%] of 87 early breast cancer receiving adjuvant chemotherapy, P = .06). Levels of E-sel and VCAM-1 decreased in response to chemotherapy ( P < .001) in both VTE+ and patients not developing VTE (VTE−). However, decrease in VECA markers was similar in VTE+ and VTE− patients, implying this is not the cause of VTE. In patients with MBC following chemotherapy, d-dimer (geometric mean) increased by 36% in the 21 patients with MBC responding to chemotherapy but steadily decreased by 11% in the 15 who progressed (day 4, P < .01), implying patients with tumor response (apoptosis) had an early hypercoagulable response. Conclusions: During chemotherapy for breast cancer, VECA is induced; however, this is not the primary mechanism for VTE. Chemotherapy-induced apoptosis may enhance hypercoagulability and initiate VTE.

Cancer-related coagulopathies

The association between cancer and thrombosis is known for years. Besides the well-recognized connection between venous thromboembolism and malignancies, there are, however, also other manifestations of cancer-related activation of coagulation and (micro)vascular dysfunction. In fact, coagulation derangements and vascular disturbances in patients with cancer cover a wide spectrum of diseases and various clinical manifestations. In this review we will highlight the mechanisms that play a role in the systemic activation of coagulation in cancer patients, in its most severe form manifested as disseminated intravascular coagulation. Clinically, disseminated intravascular coagulation (DIC) in cancer has in general a less fulminant presentation than the types of DIC complicating sepsis and trauma. A more gradual, but also more chronic, systemic activation of coagulation can proceed subclinically. The relationship between venous thromboembolism and cancer as a consequence of the hypercoagulability will be discussed as well. Furthermore, the role of perturbed endothelium in the pathogenesis of microvascular dysfunction and microangiopathy in particular in the setting of cancer and chemo- or radiotherapy will be reviewed.

Hypercoagulable states

Hypercoagulable states can be inherited or acquired. Inherited hypercoagulable states can be caused by a loss of function of natural anticoagulant pathways or a gain of function in procoagulant pathways. Acquired hypercoagulable risk factors include a prior history of thrombosis, obesity, pregnancy, cancer and its treatment, antiphospholipid antibody syndrome, heparin-induced thrombocytopenia, and myeloproliferative disorders. Inherited hypercoagulable states combine with acquired risk factors to establish the intrinsic risk of venous thromboembolism for each individual. Venous thromboembolism occurs when the risk exceeds a critical threshold. Often a triggering factor, such as surgery, pregnancy, or estrogen therapy, is required to increase the risk above this critical threshold.

Impact of chemotherapy on thrombin generation and on the protein C pathway in breast cancer patients

Although thromboembolism is a problematic complication of chemotherapy, the pathogenic mechanisms by which chemotherapeutic agents exert prothrombotic effects in vivo are unclear.The objective of this study was to examine the effects of adjuvant chemotherapy on thrombin generation, the protein C anticoagulant pathway, and microparticle tissue factor (MP TF) activity in 26 breast cancer patients (stages I to III). The patients received cyclophosphamide, 5-fluorouracil, and methotrexate, epirubicin, or doxorubicin. Plasma samples were collected on day 1 (baseline), day 2, and day 8 for the first 2 cycles of chemotherapy. Levels of thrombin-antithrombin (TAT) complexes, MP TF activity, and components of the protein C anticoagulant pathway, including protein C, activated protein C (APC), soluble thrombomodulin (sTM), and soluble endothelial protein C receptor (sEPCR), were measured. Compared to prechemotherapy baseline levels, plasma TAT, protein C, and APC were significantly different following the administration of chemotherapy (p < 0.01 for each). Plasma TAT was higher in cycle 1, day 2, and cycle 2, day 8, compared to baseline. Plasma protein C levels were lower in cycle 2, day 8, whereas plasma APC levels were lower in cycle 2, day 1, and cycle 2, day 8. No significant changes were found in plasma sEPCR, sTM, or MP TF activity. This study suggests that adjuvant chemotherapy in women with breast cancer increases thrombin generation and impairs the endothelium-based protein C anticoagulant pathway.

Arterial and venous thrombosis in cancer patients

The most frequent ultimate cause of death is myocardial arrest. In many cases this is due to myocardial hypoxia, generally arising from failure of the coronary macro- and microcirculation to deliver enough oxygenated red cells to the cardiomyocytes. The principle reason for this is occlusive thrombosis, either by isolated circulating thrombi, or by rupture of upstream plaque. However, an additionally serious pathology causing potentially fatal stress to the heart is extra-cardiac disease, such as pulmonary hypertension. A primary cause of the latter is pulmonary embolus, considered to be a venous thromboembolism. Whilst the thrombotic scenario has for decades been the dominating paradigm in cardiovascular disease, these issues have, until recently, been infrequently considered in cancer. However, there is now a developing view that cancer is also a thrombotic disease, and notably a disease predominantly of the venous circulation, manifesting as deep vein thrombosis and pulmonary embolism. Indeed, for many, a venous thromboembolism is one of the first symptoms of a developing cancer. Furthermore, many of the standard chemotherapies in cancer are prothrombotic. Accordingly, thromboprophylaxis in cancer with heparins or oral anticoagulation (such as Warfarin), especially in high risk groups (such as those who are immobile and on high dose chemotherapy), may be an important therapy. The objective of this communication is to summarise current views on the epidemiology and pathophysiology of arterial and venous thrombosis in cancer.

Peripheral arterial ischemic events in cancer patients

Thromboembolic complications are the second leading cause of death in cancer patients. In contrast to the large body of literature on venous thromboembolism (VTE), relatively few reports have focused on the pathogenesis, incidence, management and outcomes of arterial thromboembolic events in patients with malignancy. The purpose of this article is to review the current literature on the etiology, mechanisms, and prognosis of arterial thromboembolic events in cancer patients and outline appropriate screening and management guidelines that may help lower the rates of morbidity and mortality related to these events.

Hypercoagulable states

Hypercoagulable states can be inherited or acquired. Inherited hypercoagulable states can be caused by a loss of function of natural anticoagulant pathways or a gain of function in procoagulant pathways. Acquired hypercoagulable risk factors include a prior history of thrombosis, obesity, pregnancy, cancer and its treatment, antiphospholipid antibody syndrome, heparin-induced thrombocytopenia, and myeloproliferative disorders. Inherited hypercoagulable states combine with acquired risk factors to establish the intrinsic risk of venous thromboembolism for each individual. Venous thromboembolism occurs when the risk exceeds a critical threshold. Often a triggering factor, such as surgery, pregnancy, or estrogen therapy, is required to increase the risk above this critical threshold.

Stratification of Venous Thromboembolism Risk in Ovarian Cancer Patients During Chemotherapy

Background:

The prevalence of venous thromboembolism (VTE) in ovarian cancer during first-line chemotherapy (CHT) ranges between 6.4% and 10.6%. Identification of the susceptible population is crucial for effective thromboprophylaxis.

Methods:

We performed a retrospective study of all our patients with epithelial ovarian cancer who underwent ambulatory first-line CHT between 1990 and 2004. Data were collected regarding age, body mass index (BMI), previous deep vein thrombosis, pulmonary embolism (PE), menopause status, FIGO stage, grade, histology, type of surgery, residual disease, and CHT. Univariable and multivariable regression analyses were performed to assess independent prognostic factors for VTE/PE to calculate a prognostic index (PI).

Results:

Of 203 patients, 16 (7.8%) had symptomatic VTE: 15 deep vein thrombosis and 1 PE. Multivariable regression analysis found that age (P = 0.01), BMI (P = 0.01), and stage (P = 0.05) were independent prognostic factors for VTE. Age, BMI, and stage were used to calculate the PI: 0.285 × age + 0.555 × BMI + 1.110 × stage. The PI was dichotomized according to its median cutoff (5.8) to define a low (3.8% at 6 months) and a high (11.3%) VTE incidence group.

Conclusions:

Age, BMI, and stage permit to identify ovarian cancer patients with a high risk in developing symptomatic VTE during CHT.

[Cancer chemotherapy and anticoagulant prophylaxis]

The modern pathobiochemical explanation of the old clinical finding, i.e. that the occurrence of the thromboembolic complications in cancer patients is significantly higher, starts to be clarified on the basis of recent knowledge regarding the role of cancer procoagulant, the expressed tissue factor and the changes in the clotting and fibrinolytic systems. Furthermore, the presently used chemotherapeutic agents have activating effects of the coagulation system as well. The details of these phenomena, the frequently used drugs and their pathobiochemical effects are detailed in this publication. Finally, it gives an outlook regarding the new adjuvant, beneficial effects of the direct anticoagulants in malignancies.

Treatment of Superior Vena Cava (SVC) Syndrome and Inferior Vena Cava (IVC) Thrombosis in a Patient with Colorectal Cancer: Combination of SVC Stenting and IVC Filter Placement to Palliate Symptoms and Pave the Way for Port Implantation

Thrombosis of the inferior vena cava is a life-threatening complication in cancer patients leading to pulmonary embolism. These patients can also be affected by superior vena cava syndrome causing dyspnea followed by trunk or extremity swelling. We report the case of a 61-year-old female suffering from an extended colorectal tumor who became affected by both of the mentioned complications. Due to thrombus formation within the right vena jugularis interna, thrombosis of the inferior vena cava, and superior vena cava syndrome, a combined interventional procedure via a left jugular access with stenting of the superior vena cava and filter placement into the inferior vena cava was performed As a consequence, relief of the patient's symptoms, prevention of pulmonary embolism, and paving of the way for further venous chemotherapy were achieved.

Effects of the chemotherapeutic agent doxorubicin on the protein C anticoagulant pathway

Although chemotherapy treatment is associated with an increased risk of thrombosis, the pathogenic mechanisms for the thrombogenic effect of chemotherapeutic drugs are poorly understood. We hypothesize that exposure of vascular endothelial cells to chemotherapeutic agents results in the loss of a thromboresistant phenotype. In this study, we examined the effects of the chemotherapeutic agent doxorubicin on the endothelium-based protein C anticoagulant pathway. The endothelial cell protein C receptor (EPCR) and thrombomodulin are two endothelial cell surface receptors required for the conversion of zymogen protein C to the anticoagulant enzyme activated protein C. Exposure of human umbilical vein endothelial cells (HUVEC) to doxorubicin resulted in a dose- and time-dependent decrease in cell surface EPCR levels. This decrease occurred as a result of receptor shedding as well as from a down-regulation in EPCR mRNA levels. In contrast, doxorubicin treatment of HUVECs resulted in a dose- and time-dependent increase in cell surface thrombomodulin attributed to an up-regulation of thrombomodulin mRNA levels. The net effect of the doxorubicin-induced changes in EPCR and thrombomodulin levels was a decrease in the capacity of HUVECs to convert protein C to activated protein C. Preliminary studies suggest that doxorubicin free radical metabolites mediate the doxorubicin-induced changes in EPCR expression but not those of thrombomodulin expression. In summary, these results suggest that doxorubicin alters the hemostatic balance of endothelial cells by down-regulating the endothelium-based protein C anticoagulant pathway.

A phase II study of epirubicin, cisplatin and capecitabine as neoadjuvant chemotherapy in locally advanced or inflammatory breast cancer

AIM

To assess the efficacy and safety of epirubicin, capecitabine and cisplatin (EXC) combination therapy in locally advanced breast cancer (LABC) and investigate the predictive value of selected biomarkers.

METHODS

Newly diagnosed LABC patients received four 3-weekly cycles of neoadjuvant EXC (epirubicin 60 mg/m(2) day 1; capecitabine 1000 mg/m(2) bid, days 1-14; cisplatin 60 mg/m(2)day 1) and two cycles of post-operative EXC.

RESULTS

Eight (17%) of 48 patients had inflammatory breast cancer. Overall response rate was 74% (95% CI: 59-86%), including complete responses in 13% (95% CI: 5-26%). Nine (22%; 95% CI: 11-38%) of 41 patients undergoing surgery achieved pathologic complete response (pCR), giving a pCR rate of 19% (95% CI: 9-33%) in the intent-to-treat population. Haematological toxicity was manageable. The most problematic toxicities were chemotherapy-induced nausea/vomiting and hypercoagulative disorders. None of the biomarkers investigated, including HER2, predicted response.

CONCLUSION

EXC showed high efficacy in LABC, with high clinical response and pCR rate. Nausea and vomiting were unexpectedly frequent, and more aggressive prophylaxis and management of these side effects is recommended in future studies of this combination.

Reactive thrombocytosis might contribute to chemotherapy-related thrombophilia in patients with lung cancer

PURPOSE

Thrombotic risk is increased in patients with cancer and further potentiated by chemotherapy. We assessed whether early hemostatic alterations could represent a risk factor for thrombosis in patients undergoing chemotherapy for lung cancer.

PATIENTS AND METHODS

Forty-nine patients receiving chemotherapy for unresectable, locally advanced, or metastatic lung cancer were included. Blood cell count, prothrombin time, partial thromboplastin time, fibrinogen, antithrombin, D-dimers, protein C, protein S, homocysteine, folates, vitamin B12, and activated protein-C resistance were measured at day 0, +7, +15, and +21 of the first chemotherapy cycle. Factor V Leiden and FII G20210A mutations were assessed. Follow-up of patients was prospectively performed for thrombosis during all chemotherapy treatment. Factor V Leiden and FII G20210A frequency were the same as in controls.

RESULTS

Average basal levels of prothrombin time, partial thromboplastin time, antithrombin, protein C, protein S, folates, vitamin B12, and activated protein-C resistance were normal and remained stable during chemotherapy. Homocysteine, D-dimers, and fibrinogen basal levels were high but remained constant after chemotherapy. An average reduction in platelet count was recorded at day +14 in all patients after a striking increase (5.2-fold) at day +21 in the group of patients treated with gemcitabine (P < 0.001). Four thrombotic events were recorded. In all cases, thrombosis occurred within 10 days of the second or the following chemotherapy cycle with gemcitabine and cisplatin. One patient had Factor V Leiden heterozygous disease.

CONCLUSION

Our findings exclude alterations of coagulation inhibitors or activation of disseminated intravascular coagulopathy/fibrinolysis as factors that induce chemotherapy-related thrombosis in lung cancer. The temporal relationship between thrombocytosis at the time of chemotherapy administration and the clinical onset of thrombotic events suggests that thrombocytosis plays a role in triggering thrombotic complications.

Adjuvant therapy and thrombosis: How to avoid the problem?

The occurrence of thrombosis complicates the management of breast cancer because of the need for anticoagulant therapy. The pathogenesis of venous thrombosis in breast cancer is related to Virchow's triad: venous stasis, hypercoagulability related to procoagulants and vessel wall injury secondary to chemotherapy and indwelling catheters. The rate of thrombosis with tamoxifen is approximately 0.9%. There does not appear to be an increased risk of venous thrombosis with aromatase inhibitors. The thrombotic rates in patients with early stage breast cancer receiving adjuvant chemotherapy range from 3% to 8%. Thrombotic rates are higher in post-menopausal women receiving adjuvant chemotherapy and in women receiving tamoxifen in combination with chemotherapy. Thrombosis can be reduced by avoiding chemotherapy in situations where its potential efficacy is marginal. In the future, new targeted agents may avoid thrombotic complications and a number of new antithrombotic agents which are oral and do not require laboratory monitoring could be used by oncologists to prevent thrombosis.

Chemotherapy-induced thrombosis

Venous thromboembolism (VTE) is a frequent and potentially life-threatening complication associated with hematological and solid tumor malignancies. In patients with cancer, VTE portends a poor prognosis; in fact, only 12% of those who suffer an event will survive beyond one year. There are several different risk factors for the development of VTE in cancer patients that are well-described in the literature. One that has become increasingly recognized over the past two decades is the independent risk factor of chemotherapy. The annual incidence of VTE in patients receiving chemotherapy is estimated at 11%. This risk can climb to 20% or higher depending on the type of drug(s) being administered. In addition to chemotherapy, there are many other anti-neoplastic and supportive therapies that are also associated with an increased risk for the development of VTE. At present, several original basic science studies and clinical trials are underway in an effort to enhance our understanding of the mechanisms by which different chemotherapeutic agents can generate a prothrombotic state. The purpose of this article is to review the pertinent literature related to VTE in malignancy, and more specifically, chemotherapy and other cancer-related treatments associated with VTE.

Coagulopathic complications in breast cancer

Patients with cancer are highly susceptible to thromboembolic complications, which account for a significant percentage of the morbidity and mortality of the disease. Up to 15% of patients with clinically overt cancer present with venous thromboembolism during the course of their disease. Moreover, patients with cancer represent 20% of all patients in whom deep venous thrombosis and pulmonary embolism are diagnosed. This prothrombotic state in cancer can occur due to the ability of tumor cells to directly activate the blood-clotting cascade and cause thrombosis or induce procoagulant properties and inhibit anticoagulant properties of vascular endothelial cells, platelets, monocytes, and macrophages. It also is well established that this prothrombotic tendency in patients with cancer can be enhanced greatly by anticancer treatments, such as surgery and chemotherapy. This phenomenon can be seen in patients with breast cancer, particularly after surgery and chemotherapy. Increased clotting risk also is associated with the use of central venous access devices, commonly used to administer chemotherapeutic agents in patients with cancer. Thrombosis prophylaxis, therefore, should be considered for patients with breast cancer who are at risk before and during intervention. In the current review, the authors discuss the problem of thromboembolism in patients with breast cancer who are undergoing therapy, the mechanisms by which thromboembolisms occur, and the potential strategies by which these events may be prevented. Better understanding of these pathogenetic pathways may lead to the development of more targeted strategies to prevent thromboembolism in patients with cancer.

Involvement of a CD47-dependent pathway in platelet adhesion on inflamed vascular endothelium under flow

Resting platelet adhesion to inflammatory vascular endothelium is thought to play a causal role in secondary thrombus formation or microcirculatory disturbance after vessel occlusion. However, though adhesion receptors involved in platelet-matrix interactions have been extensively studied, the molecular mechanisms involved in platelet-endothelium interactions are incompletely characterized and have been mainly studied under static conditions. Using human platelets or platelets from wild-type and CD47-/- mice in whole blood, we demonstrated that at low shear rate, CD47 expressed on human and mouse platelets significantly contributes to platelet adhesion on tumor necrosis factor-alpha (TNF-alpha)-stimulated vascular endothelial cells. Using the CD47 agonist peptide 4N1K and blocking monoclonal antibodies (mAbs), we showed that CD47 binds the cell-binding domain (CBD) of endothelial thrombospondin-1 (TSP-1), inducing activation of the platelet alphaIIbbeta3 integrin that in turn becomes able to link the endothelial receptors intercellular adhesion molecule 1 (ICAM-1) and alphavbeta3. Platelet CD36 and GPIbalpha are also involved because platelet incubation with blocking mAbs directed against each of these 2 receptors significantly decreased platelet arrest. Given that anti-CD47 treatment of platelets did not further decrease the adhesion of anti-CD36-treated platelets and CD36 is a TSP-1 receptor, it appears that CD36/TSP-1 interaction could trigger the CD47-dependent pathway. Overall, CD47 antagonists may be potentially useful to inhibit platelet adhesion on inflamed endothelium.

The effects of chemotherapeutic agents on the regulation of thrombin on cell surfaces

Thromboembolic disorders are common in cancer patients. Two major contributing factors are central venous catheters for drug delivery and the use of l-aparaginase, which decreases the plasma antithrombin level, but the causes of the hypercoagulable state in these patients are not fully understood. In this study, the T24/83 cell line was used as a model to investigate the effects of chemotherapeutic agents on cell surface thrombin regulation. Plasma thrombin generation and prothrombin consumption was increased in most of the treated cells, particularly vincristine- and adriamycin-treated cells (P < 0.05), compared with controls. However, no free thrombin generation or prothrombin consumption was observed in factor VII (FVII)-depleted plasma. No significant differences in the levels of thrombin-alpha2-macroglobulin (IIa-alpha2M) and thrombin-anti-thrombin (TAT) were observed between controls and any of the treatments, except for vincristine- and adriamycin-treated cells, which showed a significant difference in TAT production (P < 0.05). Also, there was an upregulation in tissue factor (TF) mRNA expression in etoposide-, methotrexate- and vincristine-treated monolayers compared with controls, as well as an upregulation in TF protein production in vincristine-treated cells. The data suggests that thrombin generation occurs via the extrinsic (TF-dependent) coagulation pathway on cell surfaces and that some chemotherapeutic agents are able to upregulate TF mRNA and protein expression in T24/83 cells.

Chemotherapy with gemcitabine-containing regimens for locally recurrent or metastatic nasopharyngeal carcinoma

BACKGROUND

Results from Phase II trials conducted in Asia have shown that gemcitabine alone (GEM) or with cisplatin (GC) is active among patients with metastatic or locally recurrent nasopharyngeal carcinoma (NPC).

METHODS

At the Princess Margaret Hospital (PMH), Toronto, 32 patients with NPC were treated with GEM (n = 18) or GC (n = 14) from January 2000 to October 2001. Patients either received 1000 mg/m(2) GEM on Days 1, 8, and 15 every 28 days as a single agent, or with cisplatin (CG) given on day 2 at 70 mg/m(2).

RESULTS

Most patients (91%) were of Southeast Asian ancestry and 29 (91%) had Type 2 (World Health Organization 1991 classification) nonkeratinizing histology. Sixteen of the GEM (89%) and five (36%) of the GC patients had received chemotherapy before entering the study. Median follow-up was 32 weeks (range, 2-97 weeks) for both groups. In the GEM group, there were five (28%) partial responses (PR) and one (6%) complete response (CR), giving an overall response rate of 34% (95% confidence interval [CI], 13.59). In the GC group, there were two (14%) CRs and seven PRs (50%), giving an overall response of 64% (95% CI, 35-87). Hematologic toxicity was dose limiting but uncomplicated. Nonhematologic toxicity included one patient with reversible reactivation of hepatitis, one with Grade 3 cisplatin-related sensory neuropathy, and three with cardiovascular events that were possibly related to chemotherapy. The median duration of response for the GEM and GC patients was 17 and 24 weeks and the 1-year survival rate was 48% (95% CI, 18-78) and 69% (95% CI, 40-99), respectively. Median survival has not been reached.

CONCLUSIONS

Our study confirms that GEM is an active and tolerable drug for patients with NPC.

Impact of thrombophilic gene mutations on thrombosis risk in patients with gastrointestinal carcinoma

BACKGROUND

Patients with malignancies have an increased risk for thromboembolic events due to the release of tissue factor by the tumor, damage to the vessel wall, and immobilization. Moreover, tumors may improve their growth and metastatic spread by utilizing the coagulation system. To date, no information is available on the additional role of prothrombotic mutations in these patients.

METHODS

The prevalence of the factor V Leiden mutation (FVL) and the prothrombin G20210A mutation and of homozygosity for the methylenetetrahydrofolate reductase (MTHFR) C677T substitution has been analyzed in a cohort of 175 patients with gastrointestinal adenocarcinoma by the polymerase chain reaction-restriction fragment length polymorphism technique.

RESULTS

6.9% of the patients were heterozygous for FVL, 5.7% were heterozygous for the prothrombin mutation, and 9.7% were homozygous for the MTHFR C677T mutation was detected in 9.7% of patients. Compared with the normal population, we found an increased prevalence of the prothrombin G20210A substitution (5.7% vs. 0.8%, P = 0.028). Thromboses were absent in 147 patients (Group A), whereas 28 of the patients suffered from thromboses during the period following tumor diagnosis (Group B). In Group A, 6.8% of the patients and 21.4% of the patients in Group B had a thrombosis before the diagnosis of cancer (P = 0.025, odds ratio [OR] 3.7). Heterozygous FVL was present in 4.8% of the patients in Group A and in 17.9% of the patients in Group B (P = 0.026, OR 4.4). In patients with thromboses before the detection of the tumor, the risk was elevated 6.3-fold (25.0% vs 5.0%, P = 0.015). Heterozygosity for the prothrombin mutation and homozygosity for the MTHFR C677T substitution did not increase the incidence of thromboses.

CONCLUSIONS

We demonstrated a significant effect of FVL on thrombosis in patients with malignant disease. Most thromboses occurred during the first months after tumor diagnosis, implicating diagnostic and therapeutic procedures as important nongenetic risk factors for venous thromboembolism. Our data also indicate that the prothrombin G20210A mutation may be a possible cofactor in cancer pathogenesis.

Coagulation and cancer: implications for diagnosis and management

Coagulation disorders are a common problem in neoplastic patients and many factors contribute to increase the risk of thromboembolic events in these patients. An hypercoagulable state is induced by malignant cells interacting directly with hemostatic system and activating the coagulation cascade. More sensitive tests to assess an hypercoagulable state in cancer patients have been developed; even though these tests are always altered in cancer patients, none of them possess a clinical significance in terms of predictive value for the occurence of thromboembolism and disease prognosis in the individual patient. The most frequent thromboembolic complications in cancer patients are deep vein thrombosis of the lower extremities and pulmonary embolism; therefore, disseminated intravascular coagulation, thrombotic thrombocytopenic purpura or haemolytic uremic syndrome are special manifestations of neoplastic disease. Diagnosis of idiopathic deep vein thrombosis, in the absence of other risk factors, could indicate the presence of occult malignant disease; however, the need for an extensive work-up to detect malignancy is still controversial. Neoplastic patients showing a thromboembolic event should be treated with unfractioned heparin or, alternatively, with low molecular weight heparins. In order to prevent recurrence, the administration of heparin should be associated and followed by an oral anticoagulant drug. In recent years new approaches in anti-aggregation therapy have been studied, such as COX-inhibitors, cicaprost and ReoPro; further studies are needed to determine the usefulness of these molecules in treatment of malignancies.

Pathogenesis of Thrombosis in Patients with Malignancy

Cancer cells can contribute to activation of the clotting system by their capacity to produce and release procoagulant/fibrinolytic substances and inflammatory cytokines, and by their interaction with host cells (endothelial, monocytes, platelets, and neutrophils). Moreover, anticancer drugs (chemotherapy/hormone therapy) may greatly affect the risk of thromboembolic complications in cancer patients by similar mechanisms, eg, through the release of procoagulants by tumor cells, through endothelial damage, or stimulation of tissue factor production by host cells. The interactions between cancer/metastatic processes and thrombosis have been reviewed here from the pathogenetic viewpoint. We hope that better knowledge of these pathogenetic pathways will lead to the development of more targeted strategies to prevent thromboembolism in cancer patients.

Internal carotid artery occlusion in a patient with malignant peritoneal mesothelioma: is it a sign of malignancy-related thrombosis?

To our knowledge, the occlusion of arteries and platelet hyperaggregation have not been reported in patients with malignant mesothelioma. However, venous thromboembolism, especially in the pulmonary vasculature in association with thrombocytosis and hyperfibrinogenemia, are commonly noticed in this disorder. Furthermore, we detected enhanced platelet aggregation in a case of malignant peritoneal mesothelioma with internal carotid artery occlusion in whom there were postsplenectomy thrombocytosis and hyperfibrinogenemia. The possible mechanisms of ICA occlusion in this patient, including the role of MPM and postsplenectomy state, thrombocytosis, platelet functional changes, and other factors were investigated and discussed.

Differential roles of IL-1 and TNF-alpha on graft-versus-host disease and graft versus leukemia

We demonstrate an increase in graft-versus-host disease (GVHD) after experimental bone marrow transplant (BMT) when cyclophosphamide (Cy) is added to an otherwise well-tolerated dose (900 cGy) of total body irradiation (TBI). Donor T cell expansion on day +13 was increased after conditioning with Cy/TBI compared with Cy or TBI alone, although cytotoxic T lymphocyte (CTL) function was not altered. Histological analysis of the gastrointestinal tract demonstrated synergistic damage by Cy/TBI and allogeneic donor cells, which permitted increased translocation of LPS into the systemic circulation. TNF-alpha and IL-1 production in response to LPS was increased in BMT recipients after Cy/TBI conditioning. Neutralization of IL-1 significantly reduced serum LPS levels and GVHD mortality, but it did not affect donor CTL activity. By contrast, neutralization of TNF-alpha did not prevent GVHD mortality but did impair CTL activity after BMT. When P815 leukemia cells were added to the bone marrow inoculum, allogeneic BMT recipients given the TNF-alpha inhibitor relapsed at a significantly faster rate than those given the IL-1 inhibitor. To confirm that the role of TNF-alpha in graft versus leukemia (GVL) was due to effects on donor T cells, cohorts of animals were transplanted with T cells from either wild-type mice or p55 TNF-alpha receptor-deficient mice. Recipients of TNF-alpha p55 receptor-deficient T cells demonstrated a significant impairment in donor CTL activity after BMT and an increased rate of leukemic relapse compared with recipients of wild-type T cells. These data highlight the importance of conditioning in GVHD pathophysiology, and demonstrate that TNF-alpha is critical to GVL mediated by donor T cells, whereas IL-1 is not.

Mechanisms and consequences of phagocyte adhesion to endothelium

Leukocyte adhesion to endothelium is essential for the development of an appropriate immune-inflammatory response. The vital importance of leukocyte-endothelial adhesive interactions in host defense and homeostasis is illustrated by the clinical manifestations of patients with congenital defects of leukocyte adhesion functions. However, under some circumstances leukocyte adhesion to endothelium may instead lead to vascular and tissue damage. In recent years, there has been remarkable progress in the understanding of the molecular basis of leukocyte adhesion to endothelium, and this knowledge has led to a new approach to immunomodulation in human disease, ie 'antiadhesion' therapy. This review focuses on cell adhesion molecules mediating adhesion of circulating phagocytes to vascular endothelium, on congenital defects of phagocyte adhesion in man, and on the current status of antiadhesion therapy directed towards phagocyte and endothelial adhesion molecules. We will also consider markers of phagocyte activation, which may provide a means to identify those patients who would benefit most from antiadhesion therapy.

Cancer chemotherapy-related thrombotic thrombocytopenic purpura: biological evidence of increased nitric oxide production

The occurrence of thrombotic thrombocytopenic purpura (TTP) in cancer patients receiving chemotherapy has been well established; although this entity is rare, its clinical importance seems to be growing. We describe 3 cases of TTP developing in cancer patients receiving different chemotherapeutic regimens. Using a sensitive high-performance liquid chromatographic method, we evaluated the stable nitric oxide end products, nitrite and nitrate, in the plasma of these patients. Nitric oxide is one of the key components involved in maintaining the normal nonthrombogenicity of the vascular endothelium. In our 3 patients, we found increased nitrate titers that were substantially higher than those observed in patients with de novo TTP. The observed increased release of nitrate could be interpreted as the consequence of massive disruption of endothelial integrity, with consequent passive nitric oxide release in vivo, or an adaptive mechanism of the endothelium to compensate for diffuse microvascular occlusion. The 2 mechanisms may both be involved, but the normal titers of nitric oxide end products in de novo TTP suggest that the former mechanism is more important, at least in cancer chemotherapy-related TTP.

Chemotherapy and thrombosis in gynecologic malignancy

Thromboembolism is a severe and frequent problem in gynecologic malignancy. The average DVT incidence during chemotherapy of 5% might represent the lower range of incidence because < 55% of thrombotic complication manifest clinical signs. However, it seems likely that in addition to chemotherapy other risk factors such as menopausal status, BMI of patients, or type of preceding surgery must coincide before thrombosis manifests. While monitoring of patients using sophisticated coagulation tests did not identify patients' risk for DVT during chemotherapy, an evaluation of the coagulation status before initiating chemotherapy is recommended. Patients with a venous access device (e.g., indwelling central venous catheter or with port cart) are at a particularly high risk for DVT. This has to be considered when cytoreductive therapy is given. Thrombosis prophylaxis, orally or subcutaneously, should only be considered in a subpopulation of patients who offer a combination of the aforementioned risk factors. Thrombosis prevention trials during chemotherapy found a significant reduction of DVT in patients treated with anticoagulants.

Adhesion of activated platelets to endothelial cells: evidence for a GPIIbIIIa-dependent bridging mechanism and novel roles for endothelial intercellular adhesion molecule 1 (ICAM-1), alphavbeta3 integrin, and GPIbalpha

Although it has been reported that activated platelets can adhere to intact endothelium, the receptors involved have not been fully characterized. Also, it is not clear whether activated platelets bind primarily to matrix proteins at sites of endothelial cell denudation or directly to endothelial cells. Thus, this study was designed to further clarify the mechanisms of activated platelet adhesion to endothelium. Unstimulated human umbilical vein endothelial cell (HUVEC) monolayers were incubated with washed, stained, and thrombin-activated human platelets. To exclude matrix involvement, HUVEC were harvested mechanically and platelet binding was measured by flow cytometry. Before the adhesion assay, platelets or HUVEC were treated with different receptor antagonists. Whereas blockade of platelet beta1 integrins, GPIbalpha, GPIV, P-selectin, and platelet-endothelial cell adhesion molecule (PECAM)-1 did not reduce platelet adhesion to HUVEC, blockade of platelet GPIIbIIIa by antibodies or Arg-Gly-Asp (RGD) peptides markedly decreased adhesion. Moreover, when platelets were treated with blocking antibodies to GPIIbIIIa-binding adhesive proteins, including fibrinogen and fibronectin, and von Willebrand factor (vWF), platelet binding was also reduced markedly. Addition of fibrinogen, fibronectin, or vWF further increased platelet adhesion, indicating that both endogenous platelet-exposed and exogenous adhesive proteins can participate in the binding process. Evaluation of the HUVEC receptors revealed predominant involvement of intercellular adhesion molecule (ICAM)-1 and alphavbeta3 integrin. Blockade of these two receptors by antibodies decreased platelet binding significantly. Also, there was evidence that a component of platelet adhesion was mediated by endothelial GPIbalpha. Blockade of beta1 integrins, E-selectin, P-selectin, PECAM-1, vascular cell adhesion molecule (VCAM)-1 and different matrix proteins on HUVEC did not affect platelet adhesion. In conclusion, we show that activated platelet binding to HUVEC monolayers is mediated by a GPIIbIIIa-dependent bridging mechanism involving platelet-bound adhesive proteins and the endothelial cell receptors ICAM-1, alphavbeta3 integrin, and, to a lesser extent, GPIbalpha.

Synergistic effects of TNF-alpha and melphalan in an isolated limb perfusion model of rat sarcoma: a histopathological, immunohistochemical and electron microscopical study

Isolated limb perfusion (ILP) with tumour necrosis factor alpha (TNF-alpha) and melphalan has shown impressive results in patients with irresectable soft tissue sarcomas and stage III melanoma of the extremities. The mechanisms of the reported in vivo synergistic anti-tumour effects of TNF-alpha and melphalan are not precisely understood. We have developed an ILP model in the rat using a non-immunogenic sarcoma in which similar in vivo synergy is observed. The aim of this present study was to analyse the morphological substrate for this synergistic response of TNF-alpha in combination with melphalan to shed more light on the pathomechanisms involved. Histology of the tumours from saline- (n = 14) and melphalan-treated (n = 11) rats revealed apparently vital tumour cells in over 80% of the cross-sections. Interstitial oedema and coagulation necrosis were observed in the remaining part of the tumour. Haemorrhage was virtually absent. TNF-alpha (n = 22) induced marked oedema, hyperaemia, vascular congestion, extravasation of erythrocytes and haemorrhagic necrosis (20-60% of the cross-sections). Oedema and haemorrhage suggested drastic alterations of permeability and integrity of the microvasculature. Using light and electron-microscopy, we observed that haemorrhage preceded generalised platelet aggregation. Therefore, we suggest that the observed platelet aggregation was the result of the microvascular damage rather than its initiator. Remarkably, these events hardly influenced tumour growth. However, perfusion with the combination of TNF-alpha and melphalan (n = 24) showed more extensive haemorrhagic necrosis (80-90% of the cross-sections) and revealed a prolonged remission (mean 11 days) in comparison with the other groups of rats. Electron microscopical analysis revealed similar findings as described after TNF-alpha alone, although the effects were more prominent at all time points after perfusion. In conclusion, our findings suggest that the enhanced anti-tumour effect after the combination of TNF-alpha with melphalan results from potentiation of the TNF-alpha-induced vascular changes accompanied by increased vascular permeability and platelet aggregation. This may result in additive cytotoxicity or inhibition of growth of residual tumour cells.

Paradoxical influence of estrogenic hormones on platelet-endothelial cell interactions

Controversies abound in the literature about the safety and efficacy of tamoxifen and estrogen. We studied the effect of these 2 hormonal agents on factors involved in in vitro thrombogenesis: platelets and endothelial cells. Endothelial cells were derived from human umbilical veins and platelets were obtained from premenopausal and postmenopausal women, women on oral contraceptives, postmenopausal women on hormone replacement therapy, men, and patients with breast cancer who had been taking adjuvant tamoxifen for more than 1 year. The interaction of platelets with endothelial cell matrix was measured in 2 systems: 1) in a flow chamber at low shear rate and, 2) with 51Cr labeled platelets in a "static" culture system. In the static system, platelets from women on tamoxifen exhibited decreased platelet adherence to endothelial cell matrix whether they were grown in tamoxifen or control conditions, when compared to platelets from premenopausal women. When flow (25 sec-1) was added these differences were negated. Neither tamoxifen nor 17 beta estradiol had an effect on endothelial cell proliferation or platelet aggregation. Adhesion of platelets at low shear was not altered when platelet rich plasma was incubated with tamoxifen nor when endothelial cells were grown in tamoxifen. In contrast, incubation of platelets in 17 beta estradiol decreased platelet adhesion at low shear rate, however, there was no effect on platelet adhesion when endothelial cells were grown in 17 beta estradiol. We conclude that in early stages of thrombus formation as measured in vitro, tamoxifen may not have a detrimental effect and estrogen may be protective.

The importance of blood cell-vessel wall interactions in tumour metastasis

Tumour cell dissemination is a complex process, depending on the ability of malignant cells to escape from the primary tumour and penetrate and flow through the bloodstream. Circulating tumour cells can adhere to the vessel wall, dissolve the basal lamina and extravasate, giving origin to metastases. Interactions between tumour cells, blood platelets and leukocytes favour tumour cell adhesion to the vessel wall, migration in extravascular spaces and growth in secondary sites. The biochemical and molecular mechanisms regulating tumour cell adhesion to the vessel wall and intercellular contacts have been studied extensively in recent years. Moreover, it has been shown that either tumour cells or blood cells release growth factors and inflammatory proteins, such as cytokines and chemokines, that may be involved in tumour cell migration and proliferation. Finally, tumour cells and cells of the surrounding tissue possess procoagulant and fibrinolytic properties that may be important in modulating the extracellular matrix around the tumour, to allow tumour cell invasion and progression. We have described the cell types (i.e. blood platelets, leukocytes, endothelial cells), the matrix components (i.e. fibronectin, thrombospondin and laminin) and the growth factors/cytokines (i.e. platelet-derived growth factor, transforming growth factor beta, tumour necrosis factor) involved in these processes. In particular, we have described cell-cell and cell-matrix interactions, cell migration and release of growth factors, cytokines, chemotactic peptides and proteolytic enzymes. This survey has also considered a few innovative approaches for the prevention and cure of cancer and metastasis that are based on these new concepts.

Adhesion molecules and their role in cancer metastasis

This article describes various adhesion molecules and reviews evidence to support a mechanistic role for adhesion molecules in the process of cancer metastasis. A variety of evidence supports the involvement of specific adhesion molecules in metastasis. 1. For example, some cancer cells metastasize to specific organs, irrespective of the first organ encountered by the circulating cancer cells. This ability to colonize a specific organ has been correlated with the preferential adhesion of the cancer cells to endothelial cells derived from the target organ. This suggests that cancer cell/endothelial cell adhesion is involved in cancer cell metastasis and that adhesion molecules are expressed on the endothelium in an organ-specific manner. 2. Further, inclusion of peptides that inhibit cell adhesion, such as the YIGSR- or RGD-containing peptides, is capable of inhibiting experimental metastasis. 3. Metastasis can be enhanced by acute or chronic inflammation of target vessels, or by treatment of animals with inflammatory cytokines, such as interleukin-1. In vitro, cancer cell/endothelial cell adhesion can be enhanced by pretreating the endothelial cell monolayer with cytokines, such as interleukin-1 or tumor necrosis factor-alpha. This suggests that, in addition to organ-specific adhesion molecules, a population of inducible endothelial adhesion molecules is involved and is relevant to metastasis. 4. Further support for this model is found in the comparison to leukocyte/endothelial adhesion during leukocyte trafficking. Convincing evidence exists, both in vivo and in vitro, to demonstrate an absolute requirement for leukocyte/endothelial adhesion before leukocyte extravasation can occur. The relevance of this comparison to metastasis is reinforced by the observation that some of the adhesion molecules involved in leukocyte/endothelial adhesion are also implicated in cancer cell/endothelial adhesion. The involvement of adhesion molecules suggests a potential therapy for metastasis based on interrupting adhesive interactions that would augment other treatments for primary tumors.