Liver cancer is a very common disease and very difficult to treat. However, thanks to a new invention developed by an Australian company, SIRTeX Medical, incorporating products manufactured by the Australian Nuclear Science and Technology Organisation, effective treatment is now available in Australia.
"SIR-Spheres®", SIRTeX Medical's registered tradename for the product, are tiny cancer treatment weapons incorporating radioactive particles which are selectively placed in liver cancers. Quite simply, they emit radiation to kill cancer cells that in turn shield the rest of the healthy liver from most of the irradiation.
SIR-Spheres® have been approved by the Therapeutic Goods Administration for use in Australia. Primary liver cancer is common in Asia and Africa and is linked to liver damage of some kind, for example from hepatitis B and C. Secondary liver cancer is common in all countries, including Australia, and occurs through the spread of cancer from other organs to the liver. Secondary cancers may form at other sites such as in the lungs or bone; however, it is frequently the liver that fails first, causing death.
According to ANSTO's Director of Radiopharmaceuticals, Dr Stuart Carr, conventional treatment of liver cancer by chemotherapy and conventional radiation beam therapy is not effective against primary liver cancer cells.
However, the new invention developed by SIRTeX makes it possible to treat liver cancer effectively with radiation and offers a new option to patients who might otherwise be left untreated. The aim is to increase the amount of radiation specifically targeted on the tumour, while sparing the normal liver.
Professor Bruce Gray, a Medical Director of SIRTeX and formerly Professor of Surgery at the University of Western Australia, developed the technology. The treatment centres on tiny spheres of the radioactive isotope yttrium-90. This isotope emits ionising beta radiation that destroys cancer cells.
And this is where ANSTO plays its part.
To make the necessary medicine, the nuclear research reactor at Lucas Heights is used to irradiate a non-radioactive isotope of yttrium (pronounced itt-ree-umm).
"This process of irradiation usually takes three-and-a half-days," Dr Carr explained. "Each atom of the isotope, yttrium-89, captures a neutron, forming the isotope yttrium-90, which then emits beta radiation.
"The radioactive yttrium is chemically combined to form resin microspheres, and these tiny anticancer
weapons are then transported to clinics," Dr Carr said.
The spheres, which measure approximately a thousandth of a millimetre in diameter, are injected into the patient's main liver artery (the hepatic artery), one of the two vessels that supply blood to the liver.
Since liver cancer cells get blood almost exclusively from the hepatic artery, the SIR-Spheres® zero in on the caner. Only a small number of the microspheres migrate to healthy liver tissue. SIRTeX's Professor Gray explained, "Beta radiation has a short penetration distance, so more than 98 per cent of the radiation is contained within the liver, and most of this is delivered to the cancer."
The treatment, often used in combination with chemotherapy, is more precise than conventional radiotherapy, which is based on external beam sources.
SIRTeX Medical Pty Ltd, recently listed on the Australian Stock Exchange, is one of a growing number of firms commercialising Australian medical research. The company is currently applying for approval from the United States Food and Drug Administration for use of the technology in the States.