By Will Soutter
Scanning and Imaging
Detecting Cancer by
Analyzing Tissue Samples
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 Cancerous Tumours
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.
by Analyzing Tissue Samples
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.
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.