As a hepatobiliary and peritoneal surface malignancy surgical oncologist, I want to walk you through the basics of HIPEC and its role in treating peritoneal surface malignancies.
What is HIPEC?
HIPEC stands for heated intraperitoneal chemotherapy. It’s not used alone but always follows cytoreductive surgery, which involves removing all visible disease from the abdominal cavity. After that, we infuse a heated chemotherapy solution into the abdomen to eliminate microscopic disease left behind.
HIPEC should always be part of a comprehensive peritoneal surface malignancy program, whether a formal program or an informal collaboration between gastroenterology (GI), medical oncology, radiation oncology, interventional radiology, and pathology colleagues. This team-based approach is essential for proper diagnosis, staging and treatment.
Understanding peritoneal carcinomatosis
The peritoneum is a thin layer lining the abdominal cavity and covering the abdominal organs. Peritoneal carcinomatosis occurs when cancer spreads to the surface of this lining. This can affect the abdominal wall, pelvis, bowels, omentum, stomach and liver.
We use the peritoneal carcinomatosis index (PCI) score to quantify disease burden. The abdomen is divided into 13 regions, and each is scored from 0 to 3 based on tumor size. This scoring helps us evaluate whether surgery and HIPEC are feasible and beneficial.
Cytoreductive surgery and completeness scores
Cytoreduction means removing all visible disease. What that involves varies depending on where the cancer has spread. It might include removing the omentum, parts of the stomach, spleen, liver or segments of small bowel.
Once the surgery is done, we assign a completeness of cytoreduction (CCR) score:
- CCR-0: No visible disease remains
- CCR-1: Tumor nodules <2.5 mm
- CCR-2 or 3: Larger residual disease
Patients with CCR-0 or CCR-1 scores generally do significantly better than those with more residual disease.
When disease can’t be resected
Some patients are not good candidates for HIPEC because the disease can’t be safely or effectively removed. Common reasons include:
- Burden of disease is too high
- Widespread disease covering the small bowel
- Extensive tumor in the porta hepatis (where critical vessels enter the liver)
- A “frozen pelvis” where tumors obliterate surgical planes
These patients are usually treated with systemic (IV) chemotherapy alone.
The HIPEC procedure
Once cytoreduction is complete, we place inflow and outflow tubing in the abdomen. Heated saline is circulated and warmed to 42°C (about 107°F). Once that temperature is reached, we infuse chemotherapy — usually mitomycin C — and continue circulating it for 90 minutes.
The heat increases the chemotherapy’s effectiveness. Studies suggest it penetrates about 3 mm, which is why even minimal residual disease (CCR-1) can be effectively treated. After perfusion, the abdomen is washed out and closed.
How we approach different cancers
Appendix cancer
One of the original indications for HIPEC, especially for low-grade lesions. If perforated, these tumors carry a 10%-25% risk of peritoneal recurrence. In cases with visible peritoneal disease or pathological confirmation of peritoneal disease, we recommend cytoreduction and HIPEC. If no peritoneal spread is found, we usually observe.
High-grade or non-mucinous tumors are more aggressive. These patients typically receive 4-6 cycles of chemotherapy, followed by surgery and HIPEC if the disease is stable and resectable.
Colorectal cancer
About 30% of colorectal cancer patients develop peritoneal carcinomatosis. In patients with PCI scores ≤20, cytoreduction and HIPEC have been shown to improve survival. One randomized trial showed a 5-year survival of 45% with complete cytoreduction, versus nearly zero with only systemic chemotherapy.
More recent studies, including one from France, suggest that surgery alone may offer most of the benefit. That study used oxaliplatin instead of mitomycin, and its findings remain controversial. Regardless, HIPEC is often added for younger or more healthy patients.
Mesothelioma
This rare cancer nearly always presents with peritoneal spread when discovered in the abdomen. There’s no strong randomized data, but single-center studies show 5-year survival up to 75% when complete cytoreduction is achieved. Even patients with high PCI scores may benefit if the disease is resectable.
Gastric (stomach) cancer
Peritoneal spread is common in gastric cancer, occurring in over half of cases. Historically, these patients had poor outcomes. But recently, the NCCN added HIPEC to its guidelines for select patients, specifically those with PCI <10 and disease that responds to chemo.
A French study showed median survival improvement from 11 to 18.5 months in patients who underwent cytoreduction and HIPEC compared to cytoreduction alone. Several meta-analyses show a consistent survival benefit, though the absolute benefit appears modest.
Final thoughts
HIPEC is a complex but powerful tool in the treatment of peritoneal surface malignancies. It’s most effective when:
- Patients are carefully selected based on disease type, burden and performance status
- Cytoreduction can be complete or near-complete (CCR-0 or CCR-1)
- Multidisciplinary teams are involved from diagnosis to follow-up
While randomized data is limited in some cancers, the available evidence supports HIPEC as a meaningful option in well-selected patients. For the right candidate, it can improve both survival and quality of life.
Learn more about GI cancer treatment at Northside.
