On a typical day people have a coffee in the morning, walk to work, talk to friends on their mobile and even have a glass of wine with dinner.  So far today I have talked on my mobile but being ridiculously lazy on Thursdays, I have only seen the sun through glass and haven’t entered the kitchen yet!

Cancer was all over the news this week as the world health organisation (WHO) has included high mobile usage as a possible cause of cancer in their 2011 revised classifications. As I read through this list, I realised that I am regularly exposed to a variety of possible (caffeine/mobiles) and definite (UV light from the sun, alcohol) causes of cancer which lead me to the question “Why don’t we get cancer every day?”

Cancer is caused by a change in the DNA of a cell. Identical DNA is contained in the nucleus of each cell in the body and the type of cell depends on which genes in it that are switched on. Radiation, such as that released recently in Fukushima, might spring to mind when you hear about change in DNA but it can also be caused by other sources e.g. smoking, UV light. These can either directly change the DNA or they could indirectly change it by affecting one of the many vital processes that occur e.g. impairing the DNA repair process.

I had a flashback to college days when a lecturer said that a cancer cell occurs in our bodies every day but our immune system prevents it developing into a tumour. This always fascinated me as I think it embodies how amazing our body’s defence mechanisms are.

The immune system has the capability of recognising bacteria, foreign particles and cells infected by viruses. These seem obvious as it is able to tell the difference between self and non-self. However, a cancer cell is self gone wrong so how does the immune system manage to kill it? The police of our immune system include cytotoxic T cells, natural killer cells, and macrophages. They are designed to tell the difference between a normal cell and an infected/cancer cell by the composition of its surface. Once they recognise a different cell, they start a chain reaction leading to programmed cell death.

But don’t start smoking or booking sun bed sessions just yet! Cancer occurs when the immune system is overwhelmed and it overlooks a cancerous cell. This is why keeping your body in good shape can reduce your risk of cancer. Since my immune system has fought off about 9913 cancer cells so far, I think it’s time I bought it a thank you card!