Cancer is one of the biggest killers in the world, causing around 13% of deaths in 2007. Whilst there have been considerable improvements in the way cancer is treated, there is no definitive cure. When cancers are detected at an early stage, current treatments can be very effective, and the survival rate from these cases is very encouraging.
The processes which occur at the onset of cancer, as with all biological processes, happen at the nanoscale. In order to improve our ability to detect cancer at the very early stages, it is clear that we need to harness our increasing understanding of nanotechnology.
Several cancer-detection techniques are emerging which use nanotechnology to see right into the depths of the body as tumors begin to form, long before they become detectable by conventional means.
Imaging techniques, such as Magnetic Resonance Imaging (MRI) or Computed Tomography (CT) scans, can detect the presence of tumours in the body. However, by the time the tissue has altered enough to be detected by this method, the cancer has progressed to a fairly advanced stage, which may make the treatment less effective. It is also not clear from these scans whether the tomour is cancerous, or benign – a further stage of tissue analysis is needed to confirm this.
To make these scans a more robust method of testing for cancer at as early a stage as possible, a “tagging” method is required – something which will selectively bind to cancerous cells and drastically increase their visibility scans.
It seems that nanotechnology will be able to provide the solution to this problem. Metal oxide nanoparticles, which generate a very strong signal on CT and MRI scans, can be coated with antibodies which bind to a certain receptors which are produced in greater quantities in cancerous cells than in normal cells. The nanoparticles would be concentrated around cancer cells, allowing cancerous tumours to be identified very easily. The strong signal means that very early stage tumours could be detected by this technique.
Figure 1. Stanford researchers have developed a nanosensor which uses magnetic tags for biomarkers to detect cancer at a very early stage. This video explains how it works.
When it is suspected that a patient has cancer, the only way to verify it for sure is to take a biopsy – a sample of tissue which is analyzed for biomarkers – characteristic chemicals created by the disease. A technique called a fluorescent immunoassay (FIA) attaches a fluorescent “label” chemical to these biomarkers, allowing the disease to be detected.
This process could be significantly enhanced using nanotechnology. Researchers at Princeton University developed a nanomaterial, called D2PA, which amplifies the light from the fluorescent labels. This allows the cancer to be detected much earlier, when the light would normally be much too weak to detect.
Figure 2. Nanoscale gold stars shine in the presence of prostate cancer indicator. Image source: “Super-sensitive tests could detect diseases earlier” – LCN Research Highlights
Scientists at the London Centre for Nanotechnology, part of Imperial College, published research earlier this year describing a test for prostate cancer which can detect biomarkers for the disease when they are nine orders of magnitude less concentrated than the current best test can manage.
The test uses star-shaped gold nanoparticles, which are given a highly visible silver coating by an enzyme whenever the biomarker is detected.
The technique is predicted to be easily to adapt for other diseases as well.
Because cancer is not technically one single disease, but a huge number of similar diseases, there are hundreds or thousands of biomarkers which, if analyzed properly, could indicate the presence of a specific type of cancer.
An immunoassay using markers containing quantum dots could provide a much more detailed analysis of a blood or tissue sample. The wavelength of the light emitted by quantum dots depends on their size.
By attaching quantum dots of different sizes to the biomarkers for different types of cancer, a single analysis could provide doctors with a spectrum of emitted light identifying the profile of healthy and cancerous cells in the individual’s body. This could help to identify when cancer had spread to other parts of the body, allowing the best possible treatment regime to be devised.
Cancer is an issue which touches everyone at some point in their lives. A huge amount of research effort is being poured into research for diagnosis and treatment of the condition. Whilst the treatment of many common types of cancer has come on in leaps and bounds over the last few years, there is still no absolute cure for any form of cancer.
Nanotechnology features heavily in much of the research towards better treatments, diagnostic methods, and potential cures. However, in the short term, due to both technologicial and legislative restrictions, it seems likely that nano-enhanced cancer detection methods will be the first of the new wave of technologies to make its benefits felt in the medical world, and to the general public.