Cancer is a multifactorial disease, which means cancer develops due to a number of factors and not just a single factor. Vast research has been done and the understanding of the cancer has increased tremendously in the previous 3 to 4 decades regarding the various factors at play. But all of them have not been identified and still more research is needed for the same.
A term which is used quite often when talking about the cause of cancer is Risk factor. A risk factor is one which increases the probability of a person developing cancer. The person with a risk factor is at more risk of being affected by cancer when compared to a person without the risk factor. Avoidance or elimination of these risk factors can decrease the risk of a person developing cancer. risk factors can't be avoided or eliminated totally in some cases. Even in cases where risk factors can't be totally eliminated, minimization of exposure can decrease the risk of developing cancer.
Presence of a risk factors doesn't mean the person will develop cancer. Many with risk factors don't develop cancer at all.
Some of the common risk factors are
- Old age - Old age is the most important risk factor for most of the cancers. Cancer occurs due to numerous changes in the DNA. These changes occur throughout one's life. Changes to the DNA can occur during cell replication or due to damage to the DNA by environmental factors like sunlight, chemicals or infection by certain organisms. Cells of the body have built in mechanisms to repair these damages. But as a person grows old these repair mechanisms loose their efficiency and the changes accumulate in the cells. So the longer a person lives, more time for the changes to accumulate in the cells and turn cancerous. Hence cancers are common in older people. But people of all age groups can be affected by cancer including children.
- Exposure to certain chemicals or substances called carcinogens - A carcinogen is a substance or chemical which facilitates the development of cancer in a person exposed to it. Carcinogens can be found at workplaces, in our surroundings and even in our diet also. Tobacco smoke is the most common carcinogen and has been implicated in a number of cancers. Not only people who directly use tobacco but also those who are indirectly exposed to tobacco smoke are also at an increased risk of developing cancer. Not all people exposed to carcinogens develop cancer. Not everybody who smokes develops cancer. This shows there are other factors at play and shows the multifactorial nature of cancer. A person can be exposed to carcionogens at work places, as mentioned above. For example exposure to asbestos, which has been implicated in more than 90% of Mesothelioma [http://www.mesotheliomahelpinfo.com] takes place primarily at work places. Carcinogens may be found in the diet also. When food products like meat are grilled or barbecued minute quantities of carcinogens are formed which are similar to those in tobacco smoke. Some of the additives added to commercially food products may have carcinogenic potential.
- Genetic predisposition - Sometimes some individuals can inherit certain genetic mutations from their parents. These persons who inherit mutations are at an increased risk of developing cancer. Though the risk is more when compared to a person who hasn't inherited the mutation, it doesn't mean all the people who inherited a mutated gene will develop cancer. With a mutation from the start the chances of the person developing a cancer are slightly raised statistically. This is called genetic predisposition. The BRCA1 and BRCA2 genes are good examples of genetic predisposition. Women who inherit these genes have a higher risk of developing breast cancer than those who do not. Another finding of interest is the fact that most women with breast cancer do not have mutated BRCA1 and BRCA2 genes. Less than 5% of the women with breast cancer have these genes. This shows that there are other factors at work for the development of breast cancer.
- Exposure to sunlight - Ultraviolet rays emitted from sun have been implicated in the development of skin cancer. Tanning booths which are becoming quite popular are also a source of ultraviolet rays and excessive usage of tanning booths can lead to skin cancer. Protection from sunlight using proper clothing, sunscreen and avoidance of tanning booths can greatly reduce the risk of developing skin cancer.
- Exposure to radiation - Exposure to radiation like x-rays and gamma rays can damage the genes making the cells cancerous. Radiation injury is mainly implicated in leukemia's. Radiation is commonly used in medical field for diagnosis and treatment. The dose of radiation used in diagnostic procedures like x-ray and CT scanning are minimal and the risk associated with these procedures is very minute. But persons handling these kinds of instruments on a regular basis like technicians are to be extra careful and wear the protective clothing. Radiation is also used for the treatment of cancers. This form of treatment, called radiotherapy uses an higher dose of radiation than used for diagnostic procedures. Radiotherapy is associated with a much higher risk than diagnostic procedures like x-ray. It is better to consult your doctor, if you are advised to take radiotherapy, regarding the possible side effects. Most of the times the benefits outweigh the side effects. People living in the vicinity of a nuclear plant or places where atomic bombs are manufactured, tested and used are also at risk of radiation injury. The classic example is people of Hiroshima and Nagasaki. People living in these cities continue to experience the effects of radiation injury. Another source of radiation injury is radon gas, which is radioactive. People working in mines are especially at risk of exposure to radon gas. People exposed to radon gas are more prone for lung cancer. Check out cancer causes and risk factors to know more about the cancer risk factors.