This is a randomized phase II study of secondary cytoreductive surgery (CRS) in patients with relapsed ovarian cancer who have progressed on PARP inhibitor maintenance.

The primary objective is to find out whether the CRS is beneficial in patients who have progressed on PARPi maintenance.

Inclusion Criteria:

• Patients with first recurrence of platinum sensitive, invasive epithelial ovarian-, fallopian tube- or primary peritoneal cancer of any initial stage.

• Progression-free interval of at least 6 months after end of last platinum- containing therapy,

• Progressed during PARP inhibitor maintenance

• Women aged ≥ 18 years

• Complete resection of the tumor seems possible (estimated by an experienced surgeon). Intra-abdominal disease has to be excluded by MRI/CT, if other surgical approaches for isolated extra-abdominal recurrences are planned

  1. A positive AGO-score or iMODEL+PET/CT
  2. Patients who are likely to be completely resected according to the investigator's judgment will be allowed by consensus between PI(surgeon) and designated radiologist even if AGO or iMODEL+PET/CT negative.

• Patients who have given their signed and written informed consent and their consent to data transmission and -processing.

Exclusion Criteria:

• Patients with non-epithelial tumors as well as borderline tumors.
• Patients without recurrence who are scheduled for diagnostic/second-look surgery or debulking surgery after completion of chemotherapy
• More than one prior chemotherapy
• Patients with second, third, or later recurrence
• Patients with second malignancies who have been treated by laparotomy, as well as other neoplasms, if the treatment might interfere with the treatment of relapsed ovarian cancer or if major impact on prognosis is expected.
• Patients with so-called platinum-refractory tumor, i.e. progression during chemotherapy or recurrence within 6 months after end of former first platinum- containing therapy
• Only palliative surgery planned
• Radiological signs suggesting metastases not accessible to surgical removal (i.e. complete resection is deemed impossible)
• Any concomitant disease not allowing surgery and/or chemotherapy
• Any medical history indicating excessive peri-operative risk
• Any current medication inducing considerable surgical risk (e.g. bleeding: due to oral anticoagulating agents, bevacizumab)
• No assessable archival tumor tissue