A multicenter, low-intervention, drug-based study to evaluate the feasibility and safety of a combined regimen of two intraperitoneal chemotherapy modalities (used in routine clinical practice) following interval surgery for the treatment of advanced ovarian cancer. This is an independent research project (free of commercial interests).

Based on the available evidence, an optimized protocol is proposed for the radical approach to primary advanced ovarian cancer with peritoneal dissemination (FIGO III/IV). After optimal interval surgery defined as CRS + HIPEC, bidirectional therapy (BIC) will be evaluated, reproducing the scheme studied by Armstrong 8 with the modifications and recommendations of GEICO (Spanish Ovarian Cancer Research Group) 18. A series of measures are proposed to minimize the risk of complications and toxicity related to intraperitoneal treatment. All of this, with the ultimate objective of maximizing the patient's disease-free survival.

Inclusion Criteria:

• Women aged 18-70 years with a histologically proven diagnosis of FIGO stage IIIB-C/IV epithelial ovarian cancer (high-grade serous epithelial carcinoma)
• Absence of extraperitoneal disease.
• Good performance status: Karnofsky score >70 or Performance status <= 2
• Adequate liver function, defined as bilirubin <0.15 times the upper limit of normal (ULN), aspartate aminotransferase and alanine aminotransferase <= 2.5 times ULN, and alkaline phosphatase <= 3 times ULN.
• Adequate renal function, defined as serum creatinine <= 1.5 times ULN
• Acceptable bone marrow function, defined as neutrophils >1.5 x 106 L-1, hemoglobin >10 g/dL-1, and platelets >100.0 x 109 L-1
• Absence of cardiac, pulmonary, hepatic, renal, or neurological disease that contraindicates major surgery.
• Negative serum and urine pregnancy test results for women of childbearing potential at the screening visit.
• Administration of neoadjuvant chemotherapy with a total of 3 or 4 systemic cycles.
• Surgery with complete CC0 cytoreduction without digestive anastomoses.
• Patients who have signed the written IC.

Exclusion Criteria:

• Disease progression during systemic treatment with neoadjuvant chemotherapy.
• Extraperitoneal disease (including retroperitoneal lymph node metastases)
• Inability to achieve complete cytoreduction (CC-0) during preoperative (imaging) or intraoperative evaluation.
• Performance of at least one digestive anastomosis of any type. Active infection of any origin
• Allogeneic transplant, or prior bone marrow transplant, or high-dose chemotherapy with bone marrow or stem cell rescue.
• Participation in a clinical trial with an investigational drug within the last 30 days.
• Pregnant or breastfeeding women, where pregnancy is defined as the state of a woman after conception and until the end of pregnancy, confirmed by a positive human chorionic gonadotropin (hCG) test result, or who plan to become pregnant or breastfeed during study treatment or within 30 days of the end of treatment with the study drug.
• Patients with a history of allergic reactions or hypersensitivity to drugs chemically related to cisplatin and paclitaxel.
• Failure to sign written informed consent.

Twenty patients aged between 18 and 75 years, diagnosed with FIGO stage IIIB-IV epithelial ovarian cancer (high-grade serous epithelial carcinoma) and previously treated with systemic neoadjuvant chemotherapy, followed by cytoreduction + HIPEC and postoperative combined systemic and intraperitoneal chemotherapy, will be initially selected.