Ovarian cancer is the third most common gynecological malignancy worldwide. Because of late, aspecific symptoms, the disease is usually diagnosed at an advanced stage. Most patients experience recurrence and die as a result of the disease within 5 years. Treatment is a combination of surgical debulking and systemic administered chemotherapy. Intra-peritoneal (IP) chemotherapy with is currently considered the most effective treatment. In patients with at least an optimal surgical debulking, this leads to an improvement in life expectancy from 50 to 66 months. IP administration of chemotherapeutic agents is still not common practice. Furthermore recent studies revealed that cancer cells express a variety of tumor antigens, which can be targeted by the immune system. Also ovarian cancer shows evidence of a role for the immune system in clinical outcome. Novel insights into the mechanism of action of chemotherapy indicate that the efficacy of chemotherapeutic interventions are dependent on the modulation of the immune system. The impression exists that since IP chemotherapy is used, relatively more recurrences outside the abdominal cavity are observed. As of yet, no studies have described pharmacokinetics and pharmacodynamics of IP administered cisplatin and paclitaxel in the blood circulation. The investigators propose to study the use of this aspiration fluid from the IP cavity as a biomarker for the efficacy of chemotherapy intervention, monitor the effect of chemotherapy on IP tumor cells in the peritoneal cavity and monitor the effect of chemotherapy on immune cells present in the IP cavity. As well the investigators propose to correlate the presence and amount of tumor cells in peritoneal fluid with the debulking efficacy and CA 125 levels. Secondary to this the investigators intend to determine the pharmacokinetics of cisplatin and paclitaxel when administered in the IP cavity in the central circulation (plasma) as well as in the peritoneal fluid. In this observational explorative study women, aged younger than 70 years, who will receive standard IP chemotherapy for advanced epithelial ovarian cancer, who are in an adequate physical and biochemical state to receive chemotherapy are included. Immunological cell counts, tumor marker, immunological cell pathway activation and plasma concentrations of cisplatinum and paclitaxel in venous blood and in fluid aspirated from the abdominal cavity will be measured.

Inclusion Criteria:

Patients receiving IP chemotherapy and therefore meeting the following criteria:

• Primary epithelial ovarian carcinoma FIGO stage III;
• Optimal or complete primary debulking (tumor rests ≤ 1cm;
• WHO 0 - 2;
• Adequate hematological function: WBC ≥ 3. 106/L en Platelets ≥ 100. 106/L,
• Adequate renal function (Creatinine clearance >60 ml/min (Cockcroft))
• Adequate liver function tests (bilirubin and/or transaminases <1.25 UNL)

Exclusion Criteria:

A potential subject who meets any of the following criteria will be excluded from participation in this study (according to the standard IP chemotherapy):

• Intestinal stoma proximal to the flexura lienalis;
• Postoperative sepsis after primary debulking;
• Haemoglobin < 6.0 mMol/L
• Extended intraperitoneal adhesions;
• Neurotoxicity grade>1;
• Previous chemotherapy for ovarian carcinoma;
• Symptomatic hearing loss;
• Age >70 years.

Women, aged younger than 70 years, who will receive standard IP chemotherapy for advanced epithelial ovarian cancer, who are in an adequate physical and biochemical state to receive chemotherapy.