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, endometrioid carcinoma or clear cell carcinoma. * FIGO stage III-IV disease. * Selected for NACT with platinum double regimen at a multidisciplinary conference at Department of Oncology at Linköping University Hospital * Receive treatment at either of the University Hospital in Linköping, or the hospitals in Jönköping (Ryhov Hospital), Eksjö (Highland Hospital, Eksjö), Västervik (Västervik hospital), Kalmar (County Hospital, Kalmar), Värnamo (Värnamo hospital). * Planned for platinum doublet regimen. * Prior to start of NACT pregnancy should be ruled out by menstrual history or in unclear cases by a urine human chorionic gonadotropin (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). * World Health Organization (WHO) Performance Status 0-1 * Weight 50-150 kg * CA-125-level ≥250 kIU/L at diagnosis Exclusion Criteria: * Concomitant treatment with heparins, low molecular weight heparins, warfarin or nonvitamin 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 \>1. * Platinum single regimen * Estimated glomerular filtration rate (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)