'Re-plumbing' the liver helps beat cancer

[Guest guest]

From issue 2623 of New Scientist magazine, 26 September 2007, page 8

TEMPORARILY diverting blood leaving the liver during chemotherapy

could prolong the lives of people with primary or secondary liver

tumours. The hour-long procedure allows massive doses of chemotherapy

drugs to reach the liver and kill the cancer cells without poisoning

the rest of the body.

The regime involves injecting the drug straight into the liver, while

using catheters and balloons to divert the blood leaving it. This

blood is then filtered to remove most of the drug.

" The amount of drug getting to the tumour is hundreds of times more

than usual, " says Taney, president of Delcath Systems, the

New York-based company developing the procedure. Patients are given

seven times the normal dose of the chemotherapy drug melphalan, but

because the drug is prevented from spreading throughout the body its

concentration in the liver is far greater than if it had been

injected into the circulation. This increases the chances that

tumours will be killed, even if they are too small to be detected

individually.

In an early trial on 13 patients, tumours disappeared or shrank by

more than half in 10 of the patients within five weeks of their being

given the new treatment. They survived for an average of two years.

Normally around 90 per cent of people with inoperable secondary liver

tumours die within eight months of being diagnosed.

The results will be presented next month at the BioPartnering Europe

symposium in London. Delcath Systems has already begun a larger trial

in collaboration with a team led by Pingpank of the US National

Cancer Institute in Bethesda, land.

The procedure uses catheters threaded through blood vessels in the

thighs and neck, one of which delivers the drug into the hepatic

artery, which supplies the liver. Meanwhile, the inferior vena cava,

which normally drains the liver (see Diagram), is blocked by a pair

of balloons.

To maintain circulation through the liver, a tube runs through one of

these balloons. Blood leaving the liver is forced into this tube and

out of the body instead of heading for the heart. " We're capturing

the effluent, " says Taney. This blood is then passed through a filter

that removes most of the drug, before being returned to the body

through the jugular vein. The drug is infused for about 30 minutes,

and blood leaving the liver is filtered for an hour.

Adam Markham, senior medical adviser to Cancer Research UK, says any

improvements to treatments for cancer that has spread to the liver

are welcome. But he cautions that none of the previous surgical

attempts to " isolate " the liver during chemotherapy by clamping blood

vessels have worked as well as was hoped. He also warns that even

though there is no open surgery, the Delcath procedure might prove

too much for very ill patients, and that there would be a risk that

at such high concentrations the drug would damage healthy parts of

the liver.