Causes - Smoking
The causal relationship between smoking and lung cancer has been known since research began in the 1950's. Smoking related health complications kill 400,000 people each year. The fact of the matter is that smoking is said to be the single most preventable form of death in the United States. The leading cause of death among smokers is lung cancers, among which 86% of lung cancers are caused by smoking.
The process by which smoking causes lung cancer however, is somewhat more complex. This is important to understand as often the simple notion that smoking causes cancer is not compelling enough of a reason for people to quit smoking. The actual process by which the smoking causes your body to lose control of its cells may be enough for some people to eliminate a fairly irrational activity from their lifestyle.
Each cell is composed of genes which regulate the functions of the cell. One of the functions that the genes will regulate is the mitosis, or the process of cell division and reproduction. There are certain agents that have the ability to affect these genes and their functions. The only way in which the genes can be changed is the process of mutation, which can be caused by certain agents called mutagens. Once a mutagen affects a gene, it will affect the operations of the genes within the cells, including the operation of mitosis. With the addition of enough mutagens the genes can be altered to the extent that they divide and reproduce uncontrollably, a growth that eventually becomes a lung cancer tumor. Cigarette smoke contains over 4000 chemicals, many of which are known mutagen agents, thus establishing the "smoking gun" link between smoking and lung cancer.
The likelihood of a smoker developing lung cancer is also significant. A person who smokes 1 or more packs a cigarette per day has a 20-25 times better chance of developing lung cancer than someone who has never smoked. Once a person quits smoking, their chances of developing lung cancer decrease. After fifteen years of smoke free life, a person's chances of developing lung cancer are approximately those of someone who has never smoked. Cigar and pipe smoking also increases the risk of lung cancer, but not to the extent of cigarette smoking.
Unfortunately, many people who smoke want to quit but are addicted to the nicotine in the tobacco, which can be a hard habit to break. Quitting smoking however, is absolutely the most effective way to decrease one's chances of developing a potentially damning lung cancer diagnosis.