It is usually achieved by surgical removal.[1][2] When performed for curative intent, surgical debulking of tumors is known as cytoreduction or cytoreductive surgery[3] (CRS); "cytoreduction" refers to reducing the number of tumor cells. Debulking is used with curative intent in only some types of cancer, as generally partial removal of a malignant tumor is not a worthwhile intervention for curative purposes (because malignant cells left behind soon multiply and renew the threat). Ovarian cancer[4] and some types of brain tumor[5] are debulked before radiotherapy or chemotherapy begin, making those therapies more effective.