Tinzaparin And Biomarkers After Neoadjuvant Treatment of Ovarian Cancer

Inclusion Criteria: * The subject has given written consent to participate in the study. * Age 18 and above * Epithelial ovarian, fallopian tube or peritoneal cancer, or abdominal cancer where a biopsy indicates an origin from the ovary, fallopian tube or peritoneum. * Histology diagnosis of either high grade serous carcinoma, endometroid carcinoma or clear cell carcinoma. * FIGO stage III-IV disease. * Planned for platinum-based chemotherapy * Prior to start of NACT pregnancy should be ruled out by menstrual history or in unclear cases by a urine hCG test. * Women of childbearing potential should use a safe birth control method (combined hormonal contraception, progesterone only hormonal contraception, intra uterine device, bilateral tubal occlusion, vasectomized partner, sexual abstinence, male or female condom, diaphragm with spermicide). * WHO Performance Status 0-2 * Weight 50-150 kg * CA-125-level ≥250 kIE/L at diagnosis Exclusion Criteria: * Concomitant treatment with heparins, low molecular weight heparins, warfarin or non-vitamin K antagonist oral anticoagulants. Platelet inhibitors are allowed. * Treatment with heparins, low molecular weight heparins or non-vitamin K antagonist oral anticoagulants within the last year. * Known or suspected allergies against any product included in the study * Ongoing pregnancy, independent of gestational age. Breastfeeding or planned pregnancy * EOC disclosed at Cesarean section * Abdominal surgery or other major surgery within the last year * Mental inability, reluctance or language difficulties that result in difficulty understanding the meaning of study participation * Treatment or disease which, according to the investigator, can affect treatment or study results * Known brain metastasis * Participation or recent participation (within the last 30 days) in a clinical study with an investigational product * Ongoing treatment of thromboembolic disease. * Thromboembolic disease within the last year. * Hypersensitivity to the active substance (tinzaparin) or any of the excipients. * Serious hemorrhage or conditions predisposing to serious hemorrhage. Serious hemorrhage is defined as fulfilling any one of these three criteria: 1. occurs in a critical area or organ (e.g. intracranial, intraspinal, intraocular, retroperitoneal, intra-articular or pericardial, intra-uterine or intramuscular with compartment syndrome), 2. causes a fall in hemoglobin level of 20 g/L (1.24 mmol/L) or more, or 3. leads to transfusion of two or more units of whole blood or red blood cells. * Severe coagulation disorder. * Acute gastro duodenal ulcer. * Septic endocarditis. * Previous heparin-induced thrombocytopenia. * WHO Performance Status \>2. * E-GFR \<30ml/min (analyzed no more than 14 days before start of treatment with investigational product) * Platelets \<100 x10\^9/L (analyzed no more than 14 days before start of treatment with investigational product) * Treatment for other known malignancy within the last year (except basal cell carcinoma)