Prevention of Venous and Arterial Thromboembolism, in Cancer Patients Undergoing Chemotherapy, With a Low Molecular Weight Heparin (Nadroparin Calcium)

INCLUSION CRITERIA: * both sexes;aged\>18 years; * suffering from different types of malignancies(lung, breast,gastric,colon- rectum,pancreatic,ovarian,head and neck cancer)undergoing systemic chemotherapy, * having signed Informed Consent prior to initiation of any study procedure. EXCLUSION CRITERIA: * adjuvant and neo-adjuvant chemotherapy; * objectively confirmed venous or arterial thromboembolism in the last three months; * antithrombotic treatment for other indications; * life expectancy of less than 3 months; * Performance Status\>2(ECOG); * active bleeding or bleedings in the last four weeks requiring hospitalization,transfusion or surgical intervention; * bleeding diathesis(prothrombin time\<70% or activated partial thromboplastin time ratio\>1.3),or platelet count\<50x10\^9/L; * cerebrovascular hemorrhage in the last six months; * known active gastric or duodenal ulcer; * known cerebral metastasis; * cerebral aneurysm; * III-IV grade diabetic retinopathy; * severe and uncontrolled hypertension(systolic blood pressure\>180 mmHg or diastolic blood pressure\>110 mmHg); * chronic atrial fibrillation; * acute endocarditis; * acute pancreatitis; * known hypersensitivity to unfractionated heparin or LMWH; * previous occurrence of heparin-induced thrombocytopenia; * renal impairment (dependent on dialysis or creatinine higher than 2.5mg%); * liver insufficiency (alanine aminotransferase,aspartate aminotransferase,alkaline phosphatase levels\>3 times the upper limit of the normal ranges and/or total bilirubin \>3.0 mg/ml); * pregnancy or childbearing potential without adequate contraception; * treatment with other investigational drugs or patient inclusion in other clinical trials; * patients who are unable to fulfill the study requirements in terms of visits/compliance to treatment.