HIPEC stands for hyperthermic intraperitoneal chemotherapy, a procedure where heated chemotherapy is circulated directly inside the abdomen to kill microscopic cancer cells that remain after surgeons physically remove all visible tumors. It’s a two-part process: first, a major surgery called cytoreductive surgery (CRS) strips away every tumor the surgeon can see, and then a warm chemotherapy solution is bathed over the abdominal cavity for up to two hours. The entire operation typically lasts 6 to 10 hours and is reserved for cancers that have spread along the lining of the abdomen, known as the peritoneum.
How the Procedure Works
The surgery begins with cytoreduction, where surgeons systematically remove every visible tumor from the peritoneal lining. This often requires removing portions of several organs along with sections of the peritoneum itself. The goal is complete macroscopic cytoreduction, meaning no tumor deposits remain that the surgeon can see or feel. This step is considered the single most important factor in determining a patient’s outcome.
Once all visible cancer is removed, and before the abdomen is closed or the digestive tract is reconnected, the chemotherapy bath begins. The solution is warmed to about 106 to 109 degrees Fahrenheit (41 to 43 degrees Celsius) and circulated throughout the abdominal cavity. The idea is straightforward: surgery handles the tumors you can see, while the heated chemotherapy destroys the ones you can’t.
Why Heat Makes Chemotherapy Work Better
Heat and chemotherapy together are more effective than either alone. At elevated temperatures, cancer cells absorb more of the drug. The heat also increases the production of oxygen radicals inside cells, which cause additional damage, and it impairs cancer cells’ ability to repair their own DNA after the chemotherapy attacks it. Temperatures in the 39 to 43 degree Celsius range can also enhance the conversion of certain drugs into their most active forms, boosting their cancer-killing ability.
Delivering chemotherapy directly into the abdomen rather than through an IV also matters. The drug concentration at the peritoneal surface can be far higher than what you’d achieve through the bloodstream, while the rest of the body absorbs relatively little. This means the treatment hits the target area hard with fewer systemic side effects than standard intravenous chemotherapy.
Which Cancers HIPEC Treats
HIPEC targets cancers that have spread along the peritoneal lining, a pattern called peritoneal carcinomatosis. The strongest evidence currently supports its use in newly diagnosed stage III ovarian, fallopian tube, or primary peritoneal cancer, particularly in patients who have responded to initial chemotherapy and are then undergoing surgery to remove remaining disease.
For other cancers, the picture is less clear. Clinical practice guidelines note insufficient evidence to recommend HIPEC as a standard treatment for recurrent ovarian cancer, colorectal cancer that has spread to the peritoneum, gastric peritoneal disease, or peritoneal mesothelioma. That doesn’t mean it’s never used for these conditions. Many patients with appendiceal cancers or mesothelioma are referred to specialty centers for assessment and may receive HIPEC as part of a research protocol. The procedure’s role continues to evolve as more data becomes available.
Survival Outcomes
A randomized trial published in JAMA Surgery followed ovarian cancer patients for a median of nearly six years. Among patients who received HIPEC after interval surgery (surgery performed after initial chemotherapy), the results were notable: median overall survival was 61.8 months with HIPEC compared to 48.2 months without it. At the five-year mark, 52% of patients in the HIPEC group were alive, compared to 32.2% in the control group.
These benefits were specific to the interval surgery subgroup. Among patients who had primary surgery upfront (before any chemotherapy), HIPEC did not show a clear survival advantage. This highlights why patient selection matters so much: the procedure helps certain patients significantly, but it is not universally beneficial across all scenarios.
Who Qualifies for HIPEC
Not every patient with peritoneal cancer is a candidate. Surgeons use the Peritoneal Cancer Index (PCI), a scoring system that maps how much disease has spread across different regions of the abdomen, to help decide. For colorectal cancer, studies suggest that patients with a PCI score above 17 to 20 see little to no survival benefit from the procedure. The principle is simple: if there’s too much disease to remove completely, the surgery won’t achieve its goal.
Complete cytoreduction is so critical that experts agree the procedure should only be attempted when surgeons are confident they can remove all or nearly all visible disease. If the cancer involves so much of the small bowel that resection would leave too little intestine to function, the procedure is generally not offered. Patients also need to be in good enough overall health to tolerate what is a long, physically demanding operation. Because outcomes depend heavily on surgical experience, guidelines recommend that HIPEC only be performed at specialized, high-volume centers.
Risks and Complications
HIPEC combined with cytoreductive surgery is one of the most intensive operations in surgical oncology, and complication rates reflect that. Studies report overall morbidity rates between 12% and 60%, with mortality rates ranging from 0.9% to 5.8%.
Infection is the most common serious complication and the leading cause of death after the procedure. Studies report severe sepsis in 4% to 21% of patients, and infections with antibiotic-resistant organisms are not uncommon. Paralytic ileus, where the bowels temporarily stop moving, is the most frequent overall complication and contributes to about one-third of ICU readmissions. Leaks at the site where the intestines are reconnected occur in roughly 7% to 11% of cases.
Kidney injury is another significant concern, particularly when cisplatin-based chemotherapy is used. The combination of large fluid shifts during surgery, reduced blood flow to the kidneys, and the direct toxicity of the drug can impair kidney function. Reported rates of kidney problems range from 1% to 26% across different studies. In rare cases, patients require temporary or even long-term dialysis.
Recovery After HIPEC
Hospital stays typically last 6 to 12 days after the procedure. The early recovery period often involves managing pain, slowly reintroducing food as the bowels wake up, and monitoring for complications like infection or kidney function changes. Full recovery generally takes four to eight weeks, though this varies depending on the extent of surgery and whether complications arise. ICU readmission rates range from 11% to 25%, most commonly due to bowel slowdown or dehydration.
The recovery timeline reflects the scale of the operation. Patients who had multiple organs partially resected and hours of heated chemotherapy circulating through their abdomen are recovering from far more than a typical surgery. Physical stamina, appetite, and energy levels return gradually, and many patients describe the first few weeks at home as the most challenging part of the process.