Don't tell Prince Charles, but scientists in the US have turned to nanotechnology in the fight against cancer. While HRH's worries over the science of the very small sparked headlines last year about the world being consumed by "grey goo", doctors at Harvard medical school have been injecting magnetic nanoparticles to track tumours.
The millions of miniature metal balls flood the body and concentrate in healthy lymph nodes. Using medical imaging equipment, the scientists then scan cancer patients for the particles to see if their nodes are normal or malignant, which show a different pattern. This tells the doctors how far the disease has spread and influences how it is treated.
Mukesh Harisinghani, who leads the research, said: "In any type of cancer there are two things you want to know more about - the best treatment to offer the patient and the long-term prognosis. Each of those two things is related to the presence or absence of lymph node metastasis."
This metastasis, or spread, is usually determined by removing pieces of lymph tissue under anaesthetic. "This technology is a non-invasive and accurate way of doing it without cutting open your patient," Dr Harisinghani said.
The nanoparticles, each the size of a small virus and more than 1,000 times smaller than the thickness of a human hair, are made from iron oxide. They are given a sugary coating to stop them breaking down too quickly, mixed with water, and slowly injected.
The particles migrate to the lymph nodes, where they stay for up to five days before degrading. The sugar is then excreted and the iron built into red blood cells. Scientists say each nanoparticle dose provides roughly the same boost in iron levels as two steaks a week for a month.
Dr Harisinghani said it was the first clinical application of the technology for patient care.
Together with his colleague Ralph Weissleder, Dr Harisinghani gave the nanoparticles to 25 men and nine women with a range of cancers, and scanned their lymph nodes with a magnetic resonance imaging (MRI) machine.
Healthy and cancerous nodes look different because the iron oxide particles are taken up by immune cells (macrophages), which are common in normal lymph nodes but largely absent from those with cancer.
The patients in the trial had already received standard exploratory surgery to examine their lymph nodes for tumours, meaning the scientists could compare the results. The nanoparticle method identified malignant tissue 98% of the time. The results appear in the journal PLoS Medicine.
Other scientists have experimented with the iron oxide nanoparticles to image brain tumours before surgery. The Harvard pair say they are the first to train a computer to spot the difference between the healthy and diseased patterns, and to present the results as 3D reconstructions.
Radiologist Andrea Rockall is using the iron oxide balls to image gynaecological cancers at St Bart's hospital in London. "It looks a bit like Guinness and I tell the patients it's because of all the iron so they're not shocked," Dr Rockall said.
http://www.guardian.co.uk/uk_news/story/0,3604,1380106,00.html
