Hyperthermic intraperitoneal chemotherapy (HIPEC) is a special type of treatment for patients with certain cancers that have spread to the abdominal cavity (peritoneum).

Unlike regular chemotherapy, which is often delivered through an intravenous (IV) drip and then circulates throughout the entire body, HIPEC is delivered during a surgical procedure. Also called “hot chemotherapy,” HIPEC involves delivering high doses of heated chemotherapy directly to the abdomen during the surgical procedure. The chemotherapy solution is heated to about 41 to 42 degrees Celsius (about 108 F).

“Bathing the peritoneal cavity with heated chemotherapeutic agents helps to target and kill cancer cells that might be too small to remove through surgery alone,” said Alexandra Gangi, MD, director of the Gastrointestinal Tumor and Cancer Regional Therapies programs at Cedars-Sinai Cancer and associate professor at the Jim and Eleanor Randall Department of Surgery.

Gangi recently spoke with the Cedars-Sinai Newsroom about how HIPEC works and who can benefit from the targeted surgical procedure.

What is HIPEC, and who gets it?

HIPEC is a regional therapy used for patients with peritoneal disease, where cancer spreads to the peritoneum—the smooth membrane lining the abdominal wall and surrounding organs. When cancer from sites like the colon or the peritoneum itself spreads into the abdominal cavity, after removing visible tumours through surgery, heated chemotherapy is circulated in the abdomen to target and destroy remaining cancer cells at a cellular level.

Who is a good candidate for the HIPEC procedure?

Good candidates for HIPEC are patients with certain cancers that have spread within the peritoneum, a membrane that lines the inside of the abdomen and pelvis abdominal cavity. These patients have stage 4 cancer. This can include appendix cancer, colon and rectal cancer, mesothelioma, and primary peritoneal cancer. Some patients with gastric and ovarian cancer are eligible for the procedure, as well.

What does the HIPEC procedure involve?

The procedure typically begins with a cytoreductive surgery, where visible tumours are removed. Afterwards, large catheters are placed into the abdominal cavity, and the abdomen is closed. Heated chemotherapy is then circulated for 30 minutes to about an hour and a half at temperatures between 41 to 42 degrees Celsius—the solution is really hot.

Once that's done, we drain all the fluid from the belly and we open the patient back up. If there are any new surgical connections we may need to create, as in scenarios where we have removed some colon or intestine, we do that. We rinse the abdomen with saline, and then we close up the abdomen, and the patient goes to recovery.

How is HIPEC different from regular chemotherapy?

The procedure offers a more focused approach compared to regular chemotherapy, which circulates through your bloodstream throughout your body. Typically, patients won't see major fluctuations in their blood count, and they’re not necessarily considered immunocompromised. Unlike IV chemotherapy, which requires repeated sessions every few weeks, HIPEC is typically a one-time procedure, but can be repeated in some cases.

Systemic chemotherapy, which is given through an IV, relies on blood flow to reach tumours, but small tumours may not receive enough blood flow to be effectively treated this way. In HIPEC, chemotherapy is used after the visible disease is removed to kill any remaining cancer cells that exist at a cellular level, since it only penetrates about three millimetres into the abdominal wall.

How does HIPEC improve survival rates?

For certain late-stage cancers, the survival rate is quite a bit lower, at around the 20% range. However, for certain mucinous tumours like pseudomyxoma peritonei, a type of appendix cancer, HIPEC can be life-changing. The surgery significantly improves the survival rate and can reduce the risk of recurrence. In some cases, survival without recurrence can be over 80%. It's a huge range, but it is dependent on what type of cancer we're ultimately trying to treat and the patient's overall response to treatment.

What is the recovery process following the HIPEC procedure?

After surgery, some patients experience delayed return of bowel function, where the intestines take time to "wake up." This might lead to symptoms like reduced appetite, constipation or diarrhoea, depending on what was removed during the surgery. Patients may also experience some discomfort or bloating. It’s best to avoid heavy lifting for about 6-8 weeks to allow proper healing. I typically advise patients that the first three months are kind of tough. And then you kind of start to feel more like your normal self. It’s a marathon, not a sprint.