Risk Factors/Oral Cancer
posted: Apr. 10, 2013.
Understanding the causative factors of cancer will contribute to prevention of the disease. Age is frequently named as a risk factor for oral cancer, as historically it occurs in those over the age of 40. The age of diagnosed patients may indicate a time component in the biochemical or biophysicas processes of aging cells that allows malighant transformtion, or perhaps, immune system competence diminishes with age. Very recent data leads us to believe that the fastest growing segment of the oral cancer population are non-smokers under that age of fifty, which would indicate a paradigm shift in the cause of the disease, and in the locations where it most freqently occurs in the oral enviornment. The anterior of the mouth, tobacco and alchol associated cancers have declined along with a corresponding decline in smoking, and posteriorof the oral cavity sites associates with the HPV16 viral cause are increasing.
However, it is likely that the accumlative damage from other factors, such as tobacco use, alchol consumption and persistent viral infections such as HPV, are the real culprits. It may take several decades of smoking for instance, to precipitate the development of a cancer. Having said that, tobacco use in all its forms is number one on the list of risk factors in individuals ofer 50. Historically at least 75% of those diagnosed at 50 and older have been tobacco users. This percentage is now changing, and exact percentages are yet to be defitvely determined and published, as new data related to viral causes are changing the demographics very rapidly. When you combine tobacco with heavy use of alchol, your risk is signficantly increased, as the two acr synergistically. Those who both smoke and drink, have a 15 times greater risk of developing oral cancer than others.
Tobacco and alcohol are essentially chemical factors, but they can also be considered lifestyle factors, since we have some control over them. Besides these, there are physical factors such as exposure to ultraviolet radiation. This is a causative agent in cancers of the lip, as well as other skin cancers. Cancer of th lip is the one oral cancer whose numbers have declined in the last few decades. This is likelu due to the increased awarenes of the damaging effects of prolonged exposure to sunlight, and the use of sunscreens for protection. Another physical factor is exposure to x-rays. Radiographs regularly taken during examinations, and at the dental office, are safe, but overexposure over a lifetime has been implicated in several head and neck cancers.
Biological factors include viruses and funji, which have been found in assocation with oral cancers. The human papilloma virus, particularly HPV16, has been defintively implicated in oral cancers, particularly those that occur in the back or the mouth. HPV is a common, sexually transmitted virus which infects about 40 million Americans today. There are over 130 strains of HPV, the majority of which are thought to be harmlesss. Most Americans will have some version of HPV in their lifetimes, and even be exposed to the onogenic/cancer causing versions of it. But only approximatley 1% of those infected, have a lack of immune response to the HPV16 strain which is a primary causative agent in cervical cancer (with HPV18), cancers of the anus and penis, and now is a known cause of oral cancer as well. So we wish to be clear. Infection with even a high risk HPV virus does not mean that you will develop oral cancer. Most people's immune systems will clear the infection before malignancy has the opportunity to occur. It is likely that the changes in sexual behaviors of your adults over the last few decades, and which are coninuing today, are increasing the spread of HPV, and oncogenic versions of it. There are other minor risk factors which have been associated with oral cancers, but have not yet been definitvely shown to participate in their development. These include lichen planus, an inflammatory disease of the oral soft tissues, and genetic predispsitions.