Appendix cancer has often spread to the peritoneal surfaces of the abdomen by the time it is discovered. The surgery to remove as much of the cancer in the abdomen as possible, reducing the "bulk" of the cancer is called "debulking" or "cytoreduction" surgery. "Cyto" is a word root meaning cells, so cytoreduction means to surgically "reduce" number of cancer cells. Both terms mean the same thing and are usually used interchangeably.
Cytoreduction (debulking) surgery is often long and complicated and is associated with a high rate of post-operative complications. Parts of the large and small bowel along with organs or parts of organs in the abdomen that are cancerous may need to be removed during this surgery.

Cancers of the ovary and fallopian tube tend to spread to the abdominal and pelvic areas. For example, there may be cells found under the diaphragm, on the outsides of digestive organs, or in the omentum, an apron of fatty tissue roughly in front of the small intestine. During cytoreductive surgery, the surgeon carefully looks for all signs of cancer in the abdomen, and removes as much of the tumor as possible. Usually the omentum is removed as well. This makes it more likely that chemotherapy and/or radiation can kill the remaining cancer cells.

The impact of aggressive debulking surgery and cisplatin-based chemotherapy on progression-free survival in stage III and IV ovarian carcinoma
Forty consecutive patients with stage III and IV invasive ovarian carcinoma were treated on a phase II protocol consisting of optimal debulking surgery, induction cisplatin, cisplatin, doxorubicin, and cyclophosphamide (PAC) chemotherapy, 6-month interval laparoscopy, reinduction cisplatin, PAC chemotherapy, and second-look procedure. All 40 patients have either disease progression or have completed the 12- month protocol. Eighty-seven percent of the patients (35) underwent optimal (less than or equal to 2 cm residual) debulking surgery before chemotherapy, in spite of the fact that 50% (20) were referred to Roswell Park Memorial Institute (RPMI) as inoperable after initial surgery elsewhere. There were no postoperative deaths and chemotherapy was started in less than or equal to 14 days in 97% of the patients. Of the 40 patients, 30% (12) achieved a pathologic complete remission (11) or a clinical complete remission (one patient refused second-look surgery).

What is "optimal"?
It is not always technically possible to remove most or all of the visible cancer during surgery. However, we have known that combining aggressive surgery with chemotherapy has led to the best cure rates for over 20 years. Over the years, the type of chemotherapy has changed and so has the definition of how aggressive or “optimal” surgery can or should be.
Other Surgery:
Palliative surgery is used to treat complications of advanced disease. It is not intended to cure the cancer. It can also be used to correct a problem that is causing discomfort or disability. This may require surgery for effective relief. Palliative surgery may also be used to treat pain when it is hard to control by other means.
Supportive surgery is used to help with other types of treatment. For example, a vascular access device such as a catheter port can be placed into a vein to help deliver chemotherapy treatments reducing the number of needle sticks needed.