There are many different causes of cancer. While many of the causes are not completely understood, there are clear links between cancer and environmental and genetic causes. Smoking tobacco is known to greatly increase risk for many different types of cancer. There are multiple types of chemical and substances in the air that we breath, or are in the food we eat and the water we drink that are dangerous and can lead to cancer. It is also possible to inherit gene mutations from a family member. Cancers that are developed due to genetic causes account for a large percentage of cancers in the United States.

Tobacco Smoke

Smoking tobacco is known to cause many different types of cancer. Both people who smoke tobacco and those who do not have increased risk for cancer because of environmental smoke, or secondhand smoke. There are two types of second hand smoke. They are mainstream smoke and side stream smoke. Mainstream smoke is the smoke that one exhales and side stream smoke is smoke that one inhales. Second hand smoke has been to known to increase an individual's chances of getting cancer. People who do smoke tobacco are twice as likely to get cancer because of the direct smoke as well as second hand smoke from other smokers.

Tobacco smoke can lead to many types of cancer. The most common cancers caused by tobacco smoke are lung and esophageal cancer. Tobacco smoke can also lead to pancreas, cervix, kidney, and bladder cancer. More recent studies suggest that tobacco smoke may also be linked to testicular cancer. Tobacco smoke contains many carcinogens, or chemicals that can cause cancer, and can shorten average life expectancy by more than ten years.

Scientists speculate that tobacco smoke may damage important genes in the human body. These genes are the oncogenes and tumor suppressor genes. Oncogenes promote faster cell growth and division, while tumor suppressor genes slow down the rate at which cells grow and divide. A human's DNA gives these genes directions of when and how to operate. If one or both of these genes are altered, it could allow pre-cancerous cells to grow, while normal and healthy cells may grow out of control, which can lead to cancer.

Alcohol

Alcohol is another substance that has been known to cause cancer. Health care providers offer multiple theories as to how alcohol causes cancer. Some medical experts believe it disrupts the level of certain hormones, which can cause cancer, while others suggest that once alcohol is digested, it becomes a carcinogen itself. There is also another theory that it affects the oncogenes and tumor suppressor genes, like tobacco smoke does. Alcohol increases risk of getting cancer in men who have more than two drinks every twenty four hours and in women who have more than one drink in the same span of time. However, many health care providers suggest that just that amount of alcohol for each gender can be good for you in men, age fifty and older, and in women, sixty and older.

Many studies show that alcohol can be good for the cardiovascular system in older men and women. However, most do not suggest that older men and women start drinking for this reason, if they do not drink already. Since so many people drink alcohol, researchers continue to find ways to prevent and stop the health risks that alcohol can cause. People who smoke tobacco and consume alcohol are much more likely to develop cancer, because of the amount of carcinogens that they put in their body.

Genetic Causes

Many cases of cancer can be linked to genetics. Humans who develop an altered oncogene and/or tumor suppressor gene can pass that defect onto their offspring. A human's DNA is developed, in part, by their parents. Therefore, if a parent has a gene mutation, there is a possibility that they can pass it on. If a person has a family history of cancer, that does not mean that they will definitely get cancer. If a person does not have a family history of cancer, that does not mean that they will not get cancer either. However, risk for cancer increases for those that have a family history of it. Aside from the oncogenes and tumor suppressor genes, other gene mutations that are inherited are the BRCA1 and BRCA2 genes. The alteration of these genes have been linked to breast cancer as well as ovarian cancer. Like most causes of cancer, health care providers do not completely understand how gene mutations are inherited, but the evidence that they are, is obvious.

Environmental Causes

There are many different types of environmental causes of cancer. Aside from factors that deal with lifestyle decisions, such as smoking tobacco and drinking alcohol, there are many chemical and substances that we encounter and have limited control over. Asbestos consists of natural minerals that form as fibers. Once these fibers break down, they become carcinogenic. Asbestos can be inhaled or swallowed. Doing so has been known to lead to larynx, lung, gastrointestinal tract cancer, as well as mesothelioma. Asbestos comes from material that is used to insulate rooms and buildings, particularly areas that are fire proof and sound proof. In recent years, there has been many regulations passed by the government, in order to limit the amount of asbestos that is used in buildings. This is an attempt to reduce the amount of asbestos that humans are exposed to. Some experts believe that even people who live with those who are exposed to asbestos, have an increased risk of getting cancer. They believe that the asbestos could be tracked by the clothing and shoes of the individual who is exposed to asbestos.

People who come in contact with asbestos and drink alcohol, and/or smoke tobacco have a much greater risk of getting cancer. There are many chemical and substances that can increase one's risk of getting cancer. The most common include vinyl chloride, cadmium, nickel and benzene. These chemicals and substances can cause cancer alone, but create a greater risk in combination with any other causes of cancer.

Medical experts and researchers continue to find ways to limit these risks. Once more is understood about the connection between these risks and exactly how they cause cancer, more can be done to prevent them. Vaccines, drugs and regulations combined can dramatically reduce people's risk for getting cancer from both lifestyle decisions and factors that are out of their control.