Ovarian cancer most commonly follows a pattern of intraperitoneal spread, and even in the setting of bulky extra-ovarian disease, it can be thought of as being largely localized to the peritoneal compartment. This forms some of the rationale for performing extensive cytoreductive surgery (CRS) on ovarian cancer metastatic within the peritoneal cavity, and also some of the rationale for delivery of cytotoxic therapy directly to this compartment (intraperitoneal or “IP” chemotherapy). To be most effective, IP chemotherapy should be able to contact all peritoneal surfaces and be exposed to very low volume tumors (ideally no thicker than 2-mm implants).
There is a large body of evidence demonstrating the benefits of conventional IP chemotherapy in women who have received complete or “optimal” CRS to disease measuring less than 1 cm3.1 However, IP chemotherapy is complicated by difficult administration and can be difficult for patients to tolerate. It is associated with significant toxicity, more so than what is seen from intravenous chemotherapy, and this toxicity is drawn out over the 18 (or more) weeks of therapy. It requires placement of an intraperitoneal port, and there are many problems associated with this foreign body including infection, malposition, and even erosions into underlying visceral structures. There are also concerns regarding the ability of the intraperitoneal infusions to reach all peritoneal surfaces when postoperative adhesions may have formed to pocket-off areas of the peritoneal cavity.
Hyperthermic intraperitoneal chemotherapy (HIPEC), at the time of CRS, is a strategy that has been explored to overcome some of these challenges.2 HIPEC has the most history as an adjunct to the surgical management of gastrointestinal cancers (particularly appendiceal and colorectal). The technique first described by Dr. Paul H. Sugarbaker for gastrointestinal tumors remains similar to that performed in ovarian cancer.3 Patients first undergo extensive CRS until there is no macroscopic residual disease. Immediately following cytoreduction, catheters are placed into the peritoneal cavity, the main incision is temporarily closed (to prevent spillage), and an infusion of cytotoxic agents (commonly cisplatin, often with a second agent such as mitomycin C or doxorubicin) is warmed and then distilled into the peritoneal cavity until it is “moderately distended.” The patient’s body is then rolled back and forth to “wash” down the entire peritoneal cavity. All peritoneal surfaces can be touched by the agent as this procedure is happening intraoperatively prior to adhesion formation.
The “H” in HIPEC stands for hyperthermic, which is a key differentiator from traditional intraperitoneal and intravenous chemotherapy administration. Some chemotherapy agents, such as cisplatin, have a synergistic effect with hyperthermia. Some of these effects include increased oxygen free radical formation, increased cellular uptake of drug, reversal of mechanisms of drug resistance, and increases in DNA damage. The ideal range of hyperthermia is between 41° C and 44° C. At higher temperatures, infusions rates can be faster; however, higher temperatures are associated with more toxicity, particularly of the small bowel.4