HIPEC, short for hyperthermic intraperitoneal chemotherapy, is a surgical treatment that delivers heated chemotherapy directly into the abdominal cavity to kill cancer cells lining the peritoneum. The procedure pairs extensive tumor-removal surgery with a warm chemotherapy wash, typically heated to 106 to 109°F (41 to 43°C), that bathes the abdomen for 60 to 90 minutes. It’s a major operation, often lasting 8 to 10 hours, used primarily for cancers that have spread along the inner lining of the abdominal cavity.
How HIPEC Works
The procedure happens in two stages, both performed during the same operation. First, a surgeon removes as much visible tumor as possible from the abdominal cavity. This part is called cytoreductive surgery, and it can involve removing sections of the intestines, the lining of the abdomen, the spleen, or other affected organs. The goal is to leave behind no tumor larger than a grain of rice.
Once the surgical removal is complete, the HIPEC phase begins. A chemotherapy solution, warmed and maintained between 41 and 43°C, is circulated continuously through the open abdominal cavity using a system of inflow and outflow tubes connected to a heat exchanger. The warm fluid reaches surfaces that standard IV chemotherapy struggles to penetrate, coating every fold and surface inside the abdomen.
Heat does several things at once. Cancer cells are more vulnerable to high temperatures than normal cells, so the warmth itself is directly damaging. It also makes cancer cell membranes more permeable, allowing the chemotherapy to enter those cells more easily and penetrate deeper into tissue. On top of that, heat interferes with the DNA repair mechanisms cancer cells rely on to survive chemotherapy, making the drugs more effective than they would be at normal body temperature.
Because the drugs stay mostly within the abdominal cavity rather than circulating through the bloodstream, the local concentration of chemotherapy can be much higher than what IV delivery could safely achieve. This regional dose intensification is one of the key advantages of the approach.
Which Cancers HIPEC Treats
HIPEC targets cancers that have spread to the peritoneum, the thin membrane lining the abdominal cavity. These peritoneal metastases can originate from several different primary cancers. The strongest evidence supports its use in advanced ovarian cancer, where it has become part of clinical practice at many major cancer centers. For patients with stage III epithelial ovarian cancer, adding HIPEC to surgery has been shown to extend median overall survival from about 32 months to nearly 45 months, with five-year survival rates improving from roughly 26% to 38%.
For recurrent ovarian cancer that initially responded to chemotherapy, the picture is also promising. The large CHIPOR trial found that adding HIPEC to surgery at first recurrence extended median survival from about 46 months to 54 months.
Beyond ovarian cancer, HIPEC is used or being studied for appendiceal cancers (including mucinous tumors that can fill the abdomen with a jelly-like substance), colorectal cancer that has spread to the peritoneum, peritoneal mesothelioma, gastric cancer with peritoneal spread, and primary peritoneal carcinoma. For most of these cancers, evidence is still evolving, and treatment typically happens at specialized centers, often within research protocols.
Who Qualifies for the Procedure
Not everyone with peritoneal cancer is a candidate. Surgeons use a scoring system called the Peritoneal Cancer Index (PCI) to map how much disease is present across 13 regions of the abdomen. Each region is scored based on the size of the largest tumor nodule, producing a total score from 0 to 39. Research consistently identifies PCI as one of the strongest predictors of whether HIPEC will help.
For colorectal peritoneal metastases, studies suggest that patients with a PCI score above 20 are unlikely to benefit, and some data indicate the ceiling may be even lower, around 17. The logic is straightforward: if too much cancer is present, surgeons cannot remove enough of it for the chemotherapy wash to handle what remains. Beyond PCI, other factors that influence eligibility include age, whether lymph nodes are involved, and the specific tumor cell type. Certain aggressive cell types, like signet ring cell cancers, tend to respond poorly.
Cancer that has spread beyond the abdomen, to the lungs, brain, or bones, generally disqualifies a patient. HIPEC is a local treatment, and its benefit depends on disease being confined to surfaces the heated solution can reach.
What to Expect During the Operation
The combined procedure typically takes 8 to 10 hours. The cytoreductive surgery portion accounts for the majority of that time, since the surgeon is methodically inspecting and clearing every peritoneal surface. The extent of surgery varies dramatically between patients. Someone with limited disease may need only the removal of peritoneal lining, while someone with more widespread involvement may lose portions of the bowel, stomach lining, gallbladder, or reproductive organs.
After the visible tumor has been removed, the chemotherapy circulation phase lasts 60 to 90 minutes. During this time, the surgical team gently rocks or shifts the fluid to ensure it reaches all areas of the abdominal cavity. The abdomen may be left open (the “open coliseum” technique) or closed during the wash, depending on the surgical team’s approach. Once the timer finishes, the fluid is drained, any remaining surgical reconstruction is completed, and the abdomen is closed.
Recovery and Hospital Stay
Because of the length and intensity of the operation, most patients spend the first two days in the ICU for close monitoring. After that, they move to a standard hospital floor for continued recovery. The total hospital stay ranges from about 8 to 22 days, depending on which organs were removed, how the body handles the chemotherapy, and whether complications develop.
The first few weeks at home typically involve significant fatigue, limited appetite, and restricted physical activity. Many patients describe the recovery as gradual, with energy returning over two to three months. Full recovery to normal activities can take three to six months, and some patients need additional rounds of standard IV chemotherapy after they’ve healed from surgery.
Risks and Complications
HIPEC is one of the more demanding operations in surgical oncology, and complication rates reflect that. Common issues include infections, problems with surgical connections in the bowel (called anastomotic leaks), blood clots, and kidney stress from the chemotherapy agents. Some patients develop temporary or lasting changes in bowel function, particularly if large sections of intestine were removed.
The chemotherapy component adds its own risks. Even though most of the drug stays in the abdomen, some does absorb into the bloodstream, which can temporarily lower blood cell counts and suppress immune function in the weeks following surgery. Surgeons weigh these risks against the potential survival benefit, which is why careful patient selection through PCI scoring and overall health assessment matters so much. Patients who are well-nourished, physically active, and have limited disease burden tend to tolerate the procedure best and see the greatest benefit.