New research is throwing a clearer light onto some of the processes that bring about specific cancers via investigations into the basic building blocks - our cell and genes. This is allowing scientists to discover exactly how smoking or exposure to ultraviolet light can lead to cancer and also confirm if a particular environmental hazard has been the cause of a specific cancer.
Before moving on to the detail of this new work, it helps to start at the very beginning. As living creatures, we are all composed of cells - the actual number of cells in an adult human is however, interestingly enough a matter of some dispute. Figures suggest a somewhat surprising range from 10 trillion to 100 trillion. Most of these cells are regularly renewed and replaced even in adults but more so with children and growth spurting adolescents. However, some cells, such as those in the cerebral cortex for example, are never replaced.
Every cell in the body has a built in 'control mechanism' that fits it to its function and also keeps it generally operating in order. Cell growth happens when a cell divides to create two new cells - when this happens the control mechanism is also duplicated and so the new cells should be able to carry on exactly as did their 'parent' cell. This cell instruction book is in fact the DNA, chromosomes and genes that sit in the nucleus of the cell.
However, this process is not as perfect as we might like to imagine - the copies themselves are not always precise as chromosomes may mutate in the copying process and do not end up as perfect replications. Fortunately, we have a 'fail-safe' process also built into the system which is supposed to check for mutations and which will - if these mutations are dangerous - press a self destruct button and in effect, kill the damaged cell.
It is helpful, if not wholly accurate, to imagine a photocopier machine as being the key component of this cell copying process whereby a lack of toner could mean that the copies become smudged or unreadable. It is generally assumed that one of the reasons why many cancers become more prevalent with old age is that, possibly through repetition, this copying process becomes less reliable. However, it is also the case that other external factors can bring about these mutations and the way in which this can happen is still an ongoing focus of research today.
At its very simplest, cancer forms when a mutation occurs meaning that the instructions that govern the growth of a cell have failed and the cell grows in an uncontrollable way. Furthermore, the 'fail-safe' process that recognises such uncontrollable growth and shuts down the cell often also fails or in some instances, is actually overridden by the mutation itself.
Cancer research tends to work in two broad directions. Firstly, by co-relating genetic mutations to individual forms of cancer. For example, going beyond the broad category of breast cancer and narrowing it down to its different manifestations. Secondly, by seeking to track the external and environmental changes which may trigger mutations themselves.
Scientists have, over the years, highlighted some paradoxical facts. Cells combat viral infections by initiating processes that mutate the virus and rendering it 'harmless', however, in doing this the cell undergoes certain mutations itself which may actually increase the probability of it becoming cancerous.
Generally, research has used some 7,000 samples and sought to work through these with regards to the 30 most prevalent forms of cancer. This work has suggested that it is possible not only to identify many of the key mutations that lead to cancer but also to pinpoint the 'environmental' conditions ( eg smoking or exposure to UV) that were responsible for the mutation in the first instance.
Researchers have characterised these links between environmental factors and mutations as 'genetic graffiti' and the work suggests that 21 of these could account for 97% of cancer producing mutations.
This development, which builds on the explicit link between factors such as smoking - long assumed to lead towards cancer - and the precise genetic malfunction which drives the chemistry of the disease is seen as a major breakthrough that could be hugely significant for the early detection of even pre-cancerous conditions. Early detection has been the major factor driving down mortality rates for some cancers and these latest discoveries may have further impact there.
In addition, by clarifying the link between factors such as smoking, poor diet etc and cancer, the incentive to prevent cancer by avoiding these unhealthy life habits has become even more supported and will hopefully continue to have positive effects on individuals and cancer rates.