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.