Cancer can be viewed as an abnormal or altered cell that forms, replicates uncontrollably, avoids host immune response and in some cases produces proteins or hormones that it would not normally produce.  The question with cancer is what causes a cell to become abnormal and go down this path of host destruction?  When it comes to cancer, it has been theorized that there are cells that become "altered" or "cancerous" on a daily basis within our body.  It becomes the job of our immune system to recognize these altered cells and remove them from the general population before a problem develops.  Cancer can occur when at least two conditions are met.  DNA must first become sufficiently damaged so that a cell loses control of its own growth regulating mechanisms (initiation process).  The next step, promotion, occurs when normal "cross talk" between normal immune cells is altered via an "inflammatory" storm created by the cancer itself.  This is kind of like creating a smoke screen, helping the cancer cells to avoid immune response and elimination.  During the phase of promotion, one cancer cell becomes two and begins to form a mass or become organized.  The final stage is alteration of normal or programmed cell death, called apoptosis, is disrupted by inflammatory mediators.  This results in cancerous cells being allowed to exist and develop, leading to an increased blood circulation (angiogenesis), which allows the tumor to further grow and spread.
     So, the question remains as to what causes a cancerous cell to form from an otherwise normal, healthy cell?  We all are familiar with various chemicals called carcinogens that we are exposed to through tobacco use, alcohol, food sources and even in the air that we breathe.  Research has proven that these chemicals due induce cancer.  In fact, you can view a list of labeled carcinogens on the CDC website (www.cdc.org).  The question still remains as to how these carcinogens actually induce cancer in the cells and why certain individuals are more predisposed to cancer.  The fact is that all of these carcinogens are actually secondary inducers of cancer.  They have a common ground on how they induce cancer and this is what researchers are focused on at this time.  Could it be that there is a "flaw" in one person that makes them more likely to develop lung cancer from smoking versus another individual?  As a doctor, I have noted over the years that several of our patients are all exposed to the same potential carcinogen over several years, but only a small percentage actually develop cancer.  The same can be said for smoking.  Some individuals have smoked for over 40 years with the only side effect being bad breath and low grade bronchitis, while others will only smoke 10 years and have terminal lung cancer.  Let's analyze various potential theories about the initiation of cancer.  It is noted that these theories are extrapolated from human research, but should be plausible enough to cross species lines.
     The first theory to be examined is the host immune response.  Getting back to the basics, cancerous cells are theoretically formed on a daily basis and under normal circumstances, they are removed by our immune system.  So, one possible theory is that those individuals that have cancer have a weakened immune response.  Can this be proven?  Yes, there are several research papers published that show evidence that cancer patients have lower lymphocyte counts or less activity in those cell lines.  Cancer cells are actually normal cells that have become renigades.  All normal cells in our body have various "normal" or "self" proteins on their surface that literally tell the immune system that they belong there and don't kill them.  Well, in some cases, these cancerous cells still maintain those "self" proteins and thus are able to elude the immune response.  In other cases, the cells are plainly abnormal but the immune system is not strong enough to detect them and / or eliminate them from the general population.  There is a lot of evidence for an immune based theory.  As we mentioned in the Inflammatory Section, those individuals that are on long term use of steroids are predisposed to cancer.  Again, corticosteroids suppress the immune response.  AIDS patients are likewise predisposed to very rare forms of cancer.  AIDS patients have low lymphocyte counts, specifically CD4.  Those individuals under a high amount of stress, especially when coupled with a poor diet, are predisposed to cancer.  You have to keep in mind that our body is a machine, designed to self-correct and self-maintain.  The immune response is our body's army to prevent foreign invaders.  If that response is sub-optimal, then problems can and will develop.
     Along the lines of the immune system, is the second potential theory which is exposure to chronic inflammation.  As mentioned in the Inflammatory Section, our immune system as part of its normal job, secretes various proteins or cytokines into the bloodstream.  This act is very important for a ligitimate immune response.  These proteins or cytokines lead to the attraction of other cells to the area to help remove bacteria, dead tissue and aid healing.  The problem comes when the inflammatory process continues for an extended period of time.  What happens in these instances is that the cytokines and other inflammatory mediators begin to affect or influence other normal or healthy cells.  This affect can result in DNA changes within normal cells, leading to abnormal cells.  It can also lead to normal cellular death.  The daily exposure to various carcinogens can elicit inflammation in our body.  When you compound this with already existing inflammation such as with arthritis, diabetes or other health issues.... inflammatory mediators become very prevalent and can have devastating effects.  It has been noted in several areas of research that patients that are on long term antiinflammatories such as aspirin, have a lower risk of various forms of cancer.  Aspirin and other similiar medications block some of the inflammatory mediators, reducing long term damage on otherwise healthy cells.
     The third theory to be evaluated has to do with cellular oxygen utilization.  Every cell in our body has a cell wall or membrane that is from from various lipids or fats.  Depending on this composition, the fluidity of the cell can vary, making it hard to move about normally and also impacting the way the cells receives various protein signals and oxygen.  The bottom line is that the cell's ability to function normally can become impaired.  Oxygen utilization and energy production is the key for normal cell survival and function.  This theory basically can encompass two seperate viewpoints:  one being the lipid layer and the other being cellular energy production.  As mentioned, the lipid layer is composed of various fats, specifically polyunsaturated fats which are refered to as essential fatty acids (EFA's).  EFA's are not made in the body and thus we and our pets are required to consume these in our daily diet through various oils, seeds, grains and meat products.  It has been proposed that due to dietary changes in Western Civilization, and the use of more processed fats, we are not consuming the levels that we should be or that we are actually possibly consuming "adulterated" fats, which are chemically altered fats.  By doing so, these altered fats are then incorporated into the lipid layers of the cells and potentially leading to an altered function.  The second part of this theory has to do with cellular energy production.  In biochemistry terms, this is linked to the Krebb's Cycle, which is a biochemical reaction in which a cell yields energy.  The Krebb's Cycle is a complex reaction and beyond the scope of this article.  However, there are many vital nutrients needed to make sure the cycle is functioning normally and yielding appropriate energy for the body to use.  The majority of the nutrients being researched are the B-vitamins, specifically Thiamine, vitamin B6, B12 and folic acid.  All of these nutrients are vital for energy production.  So, in the end, this theory is exploring a potential defect at a cellular level that potentially leads to an altered cellular state.  Now, this theory can extend to the other two above mentioned theories.  It is possible that an altered cell, due to poor oxygen utilization or energy production, can lead to a poorly functioning immune system and also to an altered state in which inflammation runs rampant and out of control.
     The final theory to be discussed, although briefly, is the genetic theory.  In this theory, it is proposed that various DNA changes due to heredity, called oncogenes, produce an increased risk for certain individuals to develop cancer.  This seems to be a huge area of focus for research right now, especially with DNA gene mapping projects.  Is there a hereditary risk or predisposition to cancer?  I think the jury is still out on this topic and in some cases, DNA researchers are refuting their prior claims.  The future will tell.
     The most interesting thing to analyze is the past.  Cancer rates are at an all time high right now versus 50 years ago.  Some individuals are in their 80's with no health problems and have been smoking since they were in the teens.  Individuals in metropolitan areas are more likely to develop cancer than someone is a rural area that grows their own vegetables.  We are in an epidemic of cases of ADD in children, type two diabetes, autism, allergies and even cancer.  The question is what has changed over the past 50 plus years that has led us to this current trend.  Is it environmental pollution?  Is it carcinogens in our food resources?  Is it a diet high in processed fats with low nutrient value?  I don't have the answer to the problems, but I do believe the problem is man made or self induced.  Again, the basic theory is that the body is a self maintaining machine.  If problems develop, it is my theory that this is due to a deficiency or induced change secondary to our environment, which includes the air we breathe and the food we eat.