The biggest threat cancer poses happens when it spreads throughout the body.

Cancer that has spread to the lining of the abdominal cavity is particularly tricky. Once these advanced cancers have entered that area, they're notoriously difficult to treat. Surgery alone is rarely successful, and traditional chemotherapy yields limited results.

But a treatment called HIPEC offers hope.

HIPEC, which stands for hyperthermic intraperitoneal chemotherapy, involves applying heated chemotherapy directly into the abdomen after surgery.

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"For a number of different cancers, this seems to be our best opportunity to either cure or control the cancer much better than any other type of treatment," says Clifford Cho, M.D., chief of hepatopancreatobiliary and advanced gastrointestinal surgery at Michigan Medicine. "It's something that has been around for a while but recently has started to pick up speed."

Cho, who has trained in the procedure and recently introduced it at the University of Michigan Rogel Cancer Center, answered common questions about HIPEC:

How HIPEC treatment works

What kinds of cancer can this procedure treat?

Cho: This process addresses cancers that are grouped together under the term peritoneal surface malignancies, or PSM. This describes the way some cancers spread. It can encompass colon cancer, appendix cancer, mesothelioma cancer and adrenal cancer.

Mostly, we're talking about intra-abdominal cancers that, for reasons that aren't totally clear, sometimes metastasize not by getting into the bloodstream and going to different organs, but actually sort of spilling over into the abdominal cavity.

Surgery by itself has never worked well because it's impossible to get rid of all of it. It's just the nature of the way it spreads. It's like trying to pull out dandelions; you just can't get them all.

But if you combine it with HIPEC, there is some evidence that it makes a big impact.

How do you know if you qualify for HIPEC?

Cho: Some people have metastatic cancer that is spread in the body in the typical way, which is through the bloodstream. For those people, standard chemotherapy is by far the best.

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Some people have this pattern where the cancer is not so much inside the liver or inside the lungs or inside the bones, but it's more inside the lining of the belly. We rely on CAT scans and MRI scans to show us the location and distribution of the tumors, which can help us decide if someone qualifies for HIPEC.

Now, some people have both ways of developing metastatic disease — through the bloodstream and into the abdominal cavity. For those people we are careful, because it's hard to do both treatments concurrently. We have to make those decisions very carefully.

Can you describe the process?

Cho: Assuming we go through the whole process and they're good candidates, the operation itself can be very long. It really is driven more by how much tumor there is that we have to remove (from the abdomen). Sometimes the removal of the tumor portion only takes a couple of hours, but sometimes that alone can take eight or nine hours.

After we remove all the tumors we can see, we fill up the belly with chemo. It's heated chemo, so it penetrates the tissue. Basically, what we're doing is bathing any leftover cancer cells in chemotherapy. This way, you get direct contact to the cancer cells with the chemo as opposed to when you give it traditionally through a port or through a vein.

Delivering the chemo this way also means that it does not get absorbed systemically. It goes right to where the tumor cells are and doesn't have the kind of systemic side effects that we always worry about with traditional chemotherapy.

What should patients know before the operation prior to HIPEC?

Cho: The challenge with this type of disease is that it is hard to know, even with a CAT scan, exactly what the operation is going to entail.

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Sometimes we must remove multiple organs — because many times it's not just a big tumor but seeding of little tumor deposits throughout the abdominal cavity. You might not know what you will need to remove until you do the operation.

Also, because of the duration of the operation and how much tumor removal there is, oftentimes even if everything goes perfectly, people can be in the hospital for over a week. Usually the reason is because the bowel falls asleep, which is the natural response to a big operation. And because this is a bigger operation than most, that sometimes lasts longer.

Can HIPEC offer a second chance to some people who might otherwise be facing palliative care?

Cho: Under the right circumstances, yes. This is a way of treating some tumors that are otherwise just inaccessible.

For more information about HIPEC treatment, call the Cancer AnswerLine at 800-865-1125.