In advanced cancers, where complete removal is not an option, as much tumor as possible is removed in a procedure called debulking surgery. This surgery is not always successful, and is less likely to be successful in women with extensive metastases in the peritoneum, stage- IV disease, cancer in the transverse fissure of the liver, mesentery, or diaphragm, and large areas of ascites. Debulking surgery is usually only done once. Computed tomography (abdominal CT) is often used to assess if primary debulking surgery is possible, but low certainty evidence also suggests fluorodeoxyglucose‐18 (FDG) PET/CT and MRI may be useful as an addition for assessing macroscopic incomplete debulking. More complete debulking is associated with better outcomes: women with no macroscopic evidence of disease after debulking have a median survival of 39 months, as opposed to 17 months with less complete surgery. By removing metastases, many cells that are resistant to chemotherapy are removed, and any clumps of cells that have died are also removed. This allows chemotherapy to better reach the remaining cancer cells, which are more likely to be fast-growing and therefore chemosensitive.