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Cancer is one of the biggest killers in the world, causing 8.8 million deaths 2017. More than 1 in 3 people develop some form of cancer during their lifetime, and the death rate has increased from 13% in 2007 to 15.7% in 2017. 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.
In the fight against cancer, half of the battle is early detection. Nanotechnology provides new molecular contrast agents and materials, which enables earlier and more accurate initial diagnosis, as well as continual monitoring of treatment.
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.
Scanning and Imaging Cancerous Tumours
Imaging techniques such as Magnetic Resonance Imaging (MRI) and 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 making treatment less effective. It is also not clear from these scans whether the tumour is cancerous or benign, and further 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 in scans.
Metal oxide nanoparticles generate a very strong signal on CT and MRI scans and can be coated with antibodies that bind to certain receptors, which are produced in greater quantities in cancerous cells than in normal cells. The nanoparticles are concentrated around cancer cells, allowing cancerous tumours to be identified easily. The strong signal means that very early stage tumours could be detected by this technique.
Detecting Cancer by Analyzing Tissue Samples
When it is suspected that a patient has cancer a biopsy is taken. A sample of tissue is analyzed for the chemical biomarkers 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 can be 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. As cancer is not technically one single disease, there are hundreds or thousands of biomarkers that indicate the presence of a specific type of cancer.
An immunoassay using markers containing quantum dots provides a much more detailed analysis of a blood or tissue sample. When energy is applied to an atom, electrons are energised and move to a higher level. When the electron returns to its lower and stable state, this additional energy is emitted as light corresponding to a particular frequency. 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 can help to identify when cancer had spread to other parts of the body, allowing the best possible treatment regime to be devised. Other nanomaterials that can be used in a similar manner are carbon nanotubes, nanowires and nanoshells.
Nanotechnologies are being researched as a way of delivering immunotherapy. Nanoparticles are used for delivery of immunostimulatory or immunomodulatory molecule, in combination with chemotherapy and radiotherapy. Nanoparticle vaccines are being designed that raise a sufficient T cell response to eradicate tumors. This happens through co-delivery of adjuvant and, the inclusion of multiple antigens for stimulation of dendritic cell targets and continuous release of antigens for prolonged immune stimulation. Molecular blockers of immune-suppressive factors can also be co-encapsulated in nanoparticle vaccines, which alters the immune context of tumors and improve response.
Cancer is an issue which touches everyone at some point in their lives. The application of nanotechnology in cancer research and treatment has experienced exponential growth in the past few years. 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.
Sources and Further Reading
- "Cancer Nanotechnology - Going Small for Big Advances" - US Department of Health and Human Services
- "Impacts on Cancer" - National Cancer Institute
- "Global Cancer Statistics", Amhedin Jemal et al, CA, 2011. DOI: 10.3322/caac.20107
- "Nanotechnology breakthrough could dramatically improve medial tests" - Princeton University
- "Cancer Diagnosis" - News-Medical.net
This article was updated on 5th October, 2018.