There are many theories about why we get cancer individually, they range from genetic mutations through to environmental carcinogens, improper diet and the use of cell phones and other electromagnetic equipment.
I intend to look at the question form a more metaphysical perspective.
First of all, how much do we suffer from cancer? The statistic that is often cited, especially by people promoting alternative cancer cures, is that 1 in 3 people suffer from cancer at some time in their life.
At first sight this seems unbelievably high so I went looking for the source of this information and found it in statistics published by the American Cancer Society.
In the period 2002 -2004 the chance of developing invasive cancer over a lifetime (from birth - death) is 44.94% or 1 in 2 for men and 37.52% or 1 in 3 for women.
Further information from the same source tells us that 1,500 Americans are predicted to die every day from cancer in 2008 and that it is responsible for 1 in every 4 deaths. Globally, 7.6 million people died from cancer in 2007.
The only good news in this deluge of death is that the 5 year survival rate over all cancers in the US is 66% in 2008 which is up from 50% in 1975-1977.
So, from a statistical viewpoint, and assuming that the US statistics can be interpreted globally, more than 1 in 3 of us will develop invasive cancer in our lifetime and about half of those cases will prove fatal.
What is cancer? As I am not a doctor I won't attempt to answer this question from a medical perspective but more from a symbolic viewpoint.
We perceive our body to be a unique and singular organism but it is actually a colony of billions of cells acting in alignment. Each cell in our body has an individual existence, it is created, lives for a period carrying out its function and then dies and is replaced. This all happens below our level of conscious awareness but is essential for our continued existence and good health.
Our very existence is a miracle of cellular co-operation, every second of our life relies on millions of aligned and organised interactions and communications between our cells.
Cells are arranged in groups called organelles and organs and are differentiated to perform different functions, all of which are necessary to the functioning of the organism as a whole. Our cells act with a singular intention; to carry out their individual function for the good of the whole being.
Cancer happens when one or more of our cells starts to act independently; it begins to grow and multiply out of alignment with the needs of the greater body. It's as if they no longer hear or obey the needs of the body and set off to have their own existence, even though this can lead to the death of the body and therefore their own demise.
Cells don't really have much imagination, when they set off for an independent existence all that know to do is to multiply and so this is what they do, some cancer cells will also continue to perform their specialised function as they spread and multiply e.g. cells from the testis, when cancerous, can produce high levels of oestrogen throughout the body.
Cancerous cells have certain characteristics
They acquire the ability to promote their own growth and they develop the ability to ignore the anti-growth signals of the body.
They lose the ability of apoptosis (which is a mechanism that allows cells to die if their genetic material becomes corrupted) which therefore leads to unchecked growth.
They lose the capacity for senescence, leading to limitless replicative potential (immortality)
They acquire the ability to promote the formation of blood supply (angiogenesis) allowing the tumor to grow beyond the limitations of passive nutrient diffusion.
They acquire the ability to invade neighbouring tissues.
They acquire the ability to build metastases at distant sites
The completion of these multiple steps would be a very rare event without:
Loss of capacity to repair genetic errors, leading to an increased mutation rate (genomic instability), thus accelerating all the other changes.
Using the metaphysical principle of as above, so below, we can compare the situation of cells working in co-operation to sustain the body with the similar situation of human individuals being part of the larger whole that is life on earth. There are billions of us living as part of a larger organic system that includes every plant and animal species and the biosphere of the earth. Our species and individual health is totally dependant on the overall health of this greater system, sometimes personified as Gaia.
From this viewpoint we have many characteristics in common with cancer:
We have the ability to promote our own growth and ignore the antigrowth signals from Gaia (famine, drought, plague etc.) and are experiencing huge population growth globally.
We have the ability to overcome genetic limitations and experience unchecked growth through technological advances.
We are developing the ability to live longer and increase our replicative potential.
We have the ability to increase our resource supply above the limits of natural production, (the use of fossil fuels that represent past deposits of stored solar energy)
We have the ability of invading neighbouring ecosystems as evidenced by the continuing extinction of other species through human activity.
We have the ability to build colonies all over the world and do exploit every available ecosystem.
My suggestion as to why we are experiencing so much cancer is that we are behaving so much like cancer and that this behaviour is accelerated by our loss of capacity or intention to repair our errors.
The cure for our collective cancer is therefore to realign our purpose with that of the greater being of which we are a part (of which we are currently apart). As a species we act to multiply ourselves at the expense of our environment even though we know that we can't survive without a healthy environment. Unchecked, we will become a tumour that kills the body that supports us. Global warming, natural disasters and resource depletion are the signals from Gaia that are telling us to start acting for the good of the whole rather than for our own selfish gain.
On a society level we need to recognise that other cultures and societies are part of our greater being and that fighting for ideological control or resource use is ridiculous. Does your liver compete with your lungs for blood supply? No, because they recognise that they are both part of the same organism. If one country goes to war with another to secure their supply of resources but causes untold death and suffering in the other country, how is the human species better off? Ideas and ideologies that separate peoples are errors of thinking that accelerate our society level cancer behaviours.
On an individual level we need to realise that we are members of families, communities and of society and that our actions need to be aligned with the good of the society as a whole. Our individual acts of selfishness are metaphorical equivalents of the growth of individual cancer cells.
If we strive to increase our position and acquire exclusive access to resources at the expense of others we are creating ourselves as tumours. We may think that this behaviour increases our personal chance of survival but none of us can survive alone, we are all totally dependant on the survival or our communities, our societies and our planet.
We have stopped listening to our intuitive guidance which is always prompting us to act in ways that are aligned with the greater good and are acting from the viewpoint of personal ego.
We are dying of cancer at an alarming rate, I propose that unless we learn from our errors and start acting in alignment with life itself by striving to ensure that every action we take is for the betterment of the whole then cancer will continue to act to reduce our population. Like our bodies, Gaia has inbuilt systems to maintain health, if we threaten those systems then they will act to curb our growth, (increased death through disease, resource depletion and natural disasters). If we overcome those systems then we will die with the planet.