A brave new step for medicine as an organ is treated outside the body – Science Writer and Consultant: Sergio Pistoi.


A brave new step for medicine as an organ is treated outside the body

New Scientist

For the first time, cancer has been treated by removing an organ from the body, giving it radiotherapy and then re-implanting it. The out-of-body operation allows doctors to administer high doses of radiation to widespread tumours without affecting other organs.

(New Scientist vol 176 issue 2374 – 21 December 2002, page 7)

For the first time, cancer has been treated by removing an organ from the body, giving it radiotherapy and then re-implanting it. The out-of-body operation allows doctors to administer high doses of radiation to widespread tumours without affecting other organs.

Doctors in Italy used the technique to treat a 48-year-old man with multiple tumours in his liver. One year after the operation, which took 21 hours, the man is alive and well. His liver is functioning normally and the latest scans have not revealed any signs of tumours.

The team, which consists of surgeons at the San Matteo Hospital in Pavia and physicists from the local division of the National Institute of Nuclear Physics, is now waiting for approval to treat another six patients with multiple liver tumours. If these are successful, the technique could one day be used to tackle hard-to-treat cancers in other organs that can be transplanted, such as the lungs or pancreas.

The patient they have treated had had a colon tumour removed, but the cancer spread to his liver. Scans revealed no fewer than 14 tumours there, and many smaller ones were discovered during the operation. Such diffuse cancers are very difficult to treat by conventional means. The tumours proved resistant to chemotherapy. And there was little hope of killing such widespread growth with conventional radiotherapy – which usually involves focusing X-ray beams onto the target – without destroying the liver.

So doctors decided to try a method called boron neutron capture therapy, first attempted in the 1950s, in which boron atoms are attached to the amino acid phenylalanine and injected into a patient. Because they are growing quickly, tumours take up more of the compound than normal cells. The team has been working on the method since 1987 and has done extensive studies to work out the optimum dose. Two to four hours after the compound is given, a low-energy neutron beam is directed at the organ, splitting the boron into high-energy particles that mainly kill the cancer cells.

But to ensure that all cancerous cells are destroyed, an even dose of neutrons has to be given to the entire organ. That’s not easy to do in the body, where obstructions such as bones block the neutron beam. And the tissues surrounding the organ inevitably receive a large dose of radiation.

Instead the surgeons decided to remove the entire liver. The organ was placed in a Teflon bag that neutrons can pass through and taken to a research reactor nearby, where it was irradiated with neutrons. It was then re-implanted, just as in a normal liver transplant operation.

“By explanting the organ, we could give a high and uniform dose to all the liver, which is impossible to obtain inside the body without serious risk to the patient,” says Tazio Pinelli, a physicist who coordinated the work together with liver surgeon Aris Zonta. “It was a bold stroke and has stirred the interest of many in the field,” says Paul Busse, a neutron radiology expert at Harvard Medical School in Boston.

The technique has been dubbed TAORMINA after the Italian for “advanced treatment of organs by means of neutron irradiation and autotransplant”. But with only one person treated so far, it is too early to judge how safe and effective it is.

Even if the method proves effective against liver and other cancers, such a drastic operation would be reserved for patients with the worst outlook, and could only be carried out while they were still strong enough to survive the long operation.

It could also be used only in cases where the spreading cancer is restricted to one organ. Once cancers spread widely, there is little that can be done. Another problem is that there are few reactors capable of producing suitable neutron beams.

But the work could also help improve normal boron neutron capture therapy, Busse says, by improving our knowledge of what doses are safe and effective. The technique is currently being tested on patients with otherwise untreatable brain tumours – obviously without removing the organ in question.
Sergio Pistoi, Rome