The iron oxide particles that could soon prove formidable solders in the battle against cancer don't look threatening at all. In fact, they're invisible to the human eye and even to all but the most powerful microscopes. But the size of these nanoparticles, with diameters about 10,000 times smaller than that of a human hair, turns out to be their advantage since they can easily penetrate cancer cells and wreak significant damage once inside.
It might be called a Trojan horse strategy that scientists at Berlin's Charité Hospital have developed to fight a particularly aggressive form of brain cancer called glioblastoma, but which could be used to treat other forms of the disease.
The new procedure involves coating the tiny iron oxide particles with an organic substance, such as the sugar glucose, and injecting them into a malignant tumor. The tumor, which has a fast metabolism and correspondingly high energy needs, greedily sucks up the little particles masquerading as sugar pellets of a sort. Healthy cells, on the other hand, show little interest. The voraciousness of cancer cells proves to be the tumor's downfall.
Scientists then use a magnetic field to heat up the nanoparticles that have ensconced themselves in the malignant tissue to temperatures up to 45 degrees Celsius (113 degrees Fahrenheit). It has the effect of giving the cells a fever that they can't endure, since while cancer cells are ferocious, scientists have long known that heat is their Achilles' heel.
The heat destroys many of the cancer cells in and around the tumor or weakens them to a point that they are more effectively treated with radiation or chemotherapy.
The treatment, known as magnetic fluid hyperthermia, has been successfully used in extending the lives of laboratory rats which were implanted with malignant brain tumors. The rats receiving the nanotherapy lived four times as long as rats receiving no treatment.
Now the hospital reports it will try the new technique on 15 patients who are suffering from Glioblastoma mutiforme, the most common primary brain tumor and the most aggressive form of brain cancer. The life expectancy prognosis in human patients according to statistics is on average 6 months to one year.
"We expect the new method to extend the life expectancy of glioblastoma patients, Klaus Maier-Hauff, director of the project and head of neurosurgery at the teaching hospital of the Charité, told reporters.
The treatment is particularly attractive to doctors working with tumors in the brain since the nanoparticles are placed in the malignant tissue by means of an extremely precise electronic navigation system. That means they can reach tumors that lie outside the reach of conventional surgical treatment, such as those situated deep in the brain or in regions that are responsible for essential tasks like speech or motor functions.
But the heat therapy is theoretically not limited to types of brain cancer. Scientists who work with breast cancer are preparing to adopt the therapy for their own patients.
"I won't have to remove the breast if I can also work in a non-invasive way," Ingrid Hilger of the Institute for Diagnostic and Intervention Radiology at the University of Jena told the newsmagazine Der Spiegel.
She hopes that the treatment will be especially effective with breast cancer patients, since breast tumors do not lie in the immediate vicinity of essential organs. Therefore it would be possible to use higher temperatures when heating the malignant tissue.
"Ideally that means we could dispense with parallel treatments with radiation and chemotherapy," she said.
Some scientists warn against too much euphoria, saying the iron oxide nanoparticles used in the treatment could do later damage to other tissues of the body if they reached the bloodstream. But scientists working on the project say as long as the amount of metal injected into the body stays under a certain level, the danger of "nanopoisoning" is relatively low.