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Causes of Cancer
As explained in cell growth and development, cancer is causes by a genetic flaw that allows abnormal cell division and growth. A small percentage of cancers are associated with a genetic flaw that is passed through families. The genetic potential is passed from parents to children and increases the risk for certain cancers, though it does not guarantee that cancer will develop.
The majority of cancers are the result of acquired DNA mutations which are changes that develop during lifetime. It is believed that environmental factors play an important role in these mutations. Carcinogens are environmental factors that influence genetic changes in the cells. Carcinogens are everywhere. They can occur naturally, such as with radon gas or metals that are found in the soil but are also man-made, such as with pollution or tobacco products. Lifestyle choices, such as tobacco use, excess alcohol use, or poor dietary choices can introduce carcinogens and affect how your body's cells respond to these exposures.
Use of smoke-producing and smokeless tobaccos are common throughout the world. Cigarette smoking is the biggest contributing factor for cancer development and cancer death. It is associated with several types of cancer including lung, oral, head and neck, esophageal, kidney, bladder, pancreatic, colon, and rectal cancers.
Avoiding first- and secondhand smoke is one of the best ways to reduce personal cancer risk. Quitting at any age results in improved health benefits compared to people who continue to smoke.
Diet is considered a possible risk factor in a number of types of cancers, particularly colon, breast, endometrial, and gallbladder cancers. A lack of roughage and bulk in the average American diet, and high levels of dietary fats, particularly unsaturated fats, are thought to be 2 of the key dietary cancer-causing agents.
Eating a healthful, balanced diet and maintaining a healthy weight appear to be a way to decrease cancer risk.
Alcohol use is linked to certain types of cancers. These include liver, breast, stomach, and those of the mouth, throat, and esophagus. The risk of cancer increases exponentially in those who smoke or use other forms of tobacco. This is especially true for certain cancers, such as esophageal cancer.
Avoiding alcohol or drinking in moderation can help reduce this risk.
The sun is a source for ultraviolet (UV) radiation. Long-term exposure to UVA and UVB rays from the sun, sunlamps, and tanning beds cause premature aging of the skin and damage that can lead to skin cancer. The most common cancers are basal and squamous cell carcinomas, which have a high cure rate. However, melanoma, a cancer of the pigmented cells, can spread throughout the body undetected, which can be fatal.
There are several steps that can be taken to protect your skin from UV damage.
Viruses are small infectious agents that cannot reproduce on their own. Instead, they enter into living cells and cause them to produce more copies of the virus. Like cells, viruses carry genes, which they may insert into the chromosomes of the infected cell. This manipulation of the infected cell’s genetic makeup by the virus can substantially increase its risk of becoming cancerous.
Out of the many viruses we come in contact with every day, only a few have been linked to cancer. Although cancers cannot be spread from person to person, the viruses that cause them can. The following viruses are associated with specific cancers:
Repeated contact with toxins in the workplace may lead to cancer by causing damage to cellular DNA. Common workplace carcinogens include arsenic, benzene, leather dusts, tar, oils, or plastics. Cancer risks are higher for people who work in industries with these carcinogens such as mining, petroleum, leather, or coal industries. For example, mesothelioma rates are much higher in those exposed to asbestos, like construction workers, than those who are not.
Toxins can be inhaled or absorbed through the skin and lead to a variety of cancers including lung, skin, liver, leukemia, and bladder cancer.
Ionizing radiation is a known carcinogen. Unfortunately, it cannot always be avoided. One example is radon gas. Radon is the result of a natural decaying process that occurs with elements or rocks in the earth. Radon is a colorless, odorless gas that can enter homes at the lowest level that is in contact with soil. It infiltrates the atmosphere and is present in water. If you are concerned about radon exposure, testing can be done by a professional or with a home test kit.
Medical procedures increase exposure to radiation. X-rays, CT scans, or radioactive dyes are used to diagnose and treat diseases. These repeated exposures can cause cellular changes that may lead to cancer. This includes radiation therapy for cancer treatment and dental x-rays during routine visits.
Talk to your doctor or dentist about the risks of radiation exposure.
Cancer causes and risk factors. National Cancer Institute website. Available at: http://www.cancer.gov/cancertopics/causes. Accessed May 1, 2015.
Cellular and molecular basis of cancer. Merck Manual Professional Version website. Available at: http://www.merckmanuals.com/professional/hematology-and-oncology/overview-of-cancer/cellular-and-molecular-basis-of-cancer. Updated July 2013. Accessed May 1, 2015.
Known and probable human carcinogens. American Cancer Society website. Available at: http://www.cancer.org/cancer/cancercauses/othercarcinogens/generalinformationaboutcarcinogens/known-and-probable-human-carcinogens. Updated March 26, 2015. Accessed May 1, 2015.
Marieb EN. Human Anatomy and Physiology. 2nd ed. Redwood City, CA: The Benjamin/Cummings Publishing Company, Inc;1992.
Smoking and tobacco use. Centers for Disease Control and Prevention website. Available at: http://www.cdc.gov/tobacco/data%5Fstatistics/fact%5Fsheets/fast%5Ffacts/index.htm. Updated April 15, 2015. Accessed May 1, 2015.
What causes cancer? American Cancer Society website. Available at: http://www.cancer.org/cancer/cancercauses/index. Accessed May 1, 2015.
- Reviewer: Mohei Abouzied, MD
- Review Date: 01/2016
- Update Date: 05/01/2015