Cancer Prevention

Cancer Prevention

Reviewed By:
Martin E. Liebling, M.D., FACP

Summary

Cancer is characterized by the presence of abnormal, malignant cells in the body. Cancer develops when the DNA within cells becomes damaged and it is not repaired by the body.

Scientists continue to study the reasons for the development of cancer. In many cases, the risk factors for cancer cannot be controlled. Age, for instance, is considered a risk factor because the chances of cancer developing increase as people grow older. Family medical history also plays a role in whether a person has a higher likelihood of developing some cancers.

Although some risk factors are unavoidable, other factors can be controlled. There are substances that have been clearly linked with cancer. These substances are known as carcinogens and use or exposure to carcinogens can increase the risk for certain cancers. Smoking, for instance, clearly causes lung cancer and many head and neck cancers.

Simple lifestyle modifications and precautions, such as not smoking, limiting alcohol consumption and limiting exposure to ultraviolet rays, can help reduce the risk of some cancers. In addition to reducing lifestyle risks, cancer can be prevented through early detection and risk assessment. Regular screenings have dramatically improved the survival rates for many cancers, such as breast cancer, cervical cancer and prostate cancer.

About cancer prevention

Cancer occurs when the cells in the body grow out of control. Healthy cells divide and grow in an organized manner. Cancer cells, on the other hand, continue to divide until they form a large mass called a tumor. This uncontrollable cell division occurs when a cell’s DNA, which directs all of the cell’s activities, sustains unrepaired damage.

There are many different types of cancer, which typically begins in one part of the body, such as an organ (e.g., prostate) or tissue (e.g., breast).  If the disease is not detected and treated in its early stages, it can spread (metastasize) to other tissues and organs in the body. According to the American Cancer Society (ACS), cancer will affect about one out of every two men and one out of every three women in the United States at some point in their lives.

Though scientists do not understand exactly why DNA sustains damage, various factors have been identified that can increase an individual’s likelihood of developing cancer. These are called risk factors. Individuals who are aware of the risk factors associated with cancer can often prevent the disease by exercising certain cautionary measures, such as avoiding known carcinogens (cancer-causing agents).

Several elements can be examined to help identify a person’s risk of cancer. It is important to note that such measures do not mean an individual will develop cancer, only that there is greater susceptibility. Knowing the information can allow individuals to take preventive measures and be monitored by a physician. These factors include:

  • An individual’s medical history. For example, hepatitis or cirrhosis may lead to liver cancer. Dialysis increases the risk of kidney cancer. Having an undescended testicle (cryptorchidism) raises a man’s chance of getting testicular cancer.

  • Family history of hereditary cancer or syndromes. Certain cancers have stronger genetic links than others. Women who have a mother, sister or daughter with breast cancer have a greater risk for developing the disease. Also, certain syndromes can increase a person’s risk, such as familial adenomatous polyposis (FAP). Individuals with this condition are prone to colorectal cancer.
  • Genetic testing. For example, having mutations of BRCA genes increases the risk of breast cancer in women and prostate cancer in men.

Preventive measures recommended by a physician depend on how much of an increased risk exists. For example, without treatment, people with FAP almost always develop colorectal cancer by age 40. Many of them undergo preventive removal of the colon (colectomy) to minimize this risk. Some women at high risk of breast cancer choose to have prophylactic mastectomy. In addition, women with breast cancer may be at increased risk to develop ovarian cancer. Breast cancer patients may choose to have their ovaries removed (oophorectomy) to prevent development of cancer there.

A physician may recommend increased monitoring rather than preventive treatments for people who face only a moderately increased risk of cancer. For example, a man susceptible to prostate cancer could undergo increased screenings with the digital rectal exam and  blood test for the tumor marker prostate-specific antigen. A woman susceptible to breast cancer could undergo mammograms with increased frequency at an earlier age or with increased frequency. The methods to monitor at-risk individuals for cancer are best determined by the patient’s physicians.

Lifestyle factors and cancer prevention

Certain lifestyle factors can increase a person’s risk of developing cancer. The term lifestyle factor refers to an individual’s behaviors and habits. Eating a vegetarian diet and exercising daily are lifestyle factors. More than 70 percent of cancers may be linked to lifestyle factors. Therefore, individuals can often prevent cancer by changing unhealthy lifestyle choices. Lifestyle factors that increase cancer risk include:

  • Tobacco use. According to the American Cancer Society (ACS), cigarette smoking causes approximately 87 percent of lung cancer deaths and at least 30 percent of all cancer deaths. The use of cigarettes and other tobacco products has been linked to cancers of the pancreas, bladder, liver, kidney, stomach, uterine cervix, rectum, colon and some leukemias. Tobacco products such as cigarettes, cigars, pipe and smokeless tobacco and snuff have more than 60 compounds that are cancer-causing agents (carcinogens). The most important action a person can take  to reduce his or her cancer risk is to quit (or never begin) smoking.

  • Alcohol consumption. Many cancers may be prevented by limiting the consumption of alcohol. Heavy alcohol consumption has been associated with cancers of the breast, liver, esophagus, larynx (voice box), pharynx (throat) and mouth. The ACS recommends that women consume no more than one alcoholic drink per day and men consume no more than two alcoholic drinks per day. A drink is defined as:
    • 12 ounces (0.35 liters) of beer
    • 5 ounces (0.15 liters) of wine
    • 1.5 ounces (0.04 liters) of distilled spirits (80 proof)

  • Diet. One of the main benefits of good nutrition is that it reduces the risk of various diseases, including certain cancers. According to the ACS, there is a direct link between dietary choices and 30 to 40 percent of cancers. The ACS’s dietary guidelines for cancer prevention recommend that individuals:
    • Eat at least five servings of fruits and vegetables every day

    • Choose whole grains instead of refined (processed) grains and sugars

    • Limit red meat consumption, especially processed meats and those high in fat

    • Select foods that help achieve and maintain a healthy weight

    • Limit salt intake

      Additionally, safe methods of food preparation, such as baking, poaching or broiling (instead of grilling or frying), may also help prevent cancer.

  • Physical activity. Regular exercise is considered an effective means of preventing cancer in many individuals. The ACS recommends that adults engage in moderate physical activity for at least 30 minutes on five or more days of the week. Moderate or vigorous exercise for a minimum of 45 minutes on five or more days each week may further reduce the likelihood of developing breast or colon cancer. The ACS recommends that children and adolescents engage in at least one hour of moderate-to-vigorous exercise at least five days a week to lower their cancer risk.

  • Sexual activity. Certain kinds of sexual behavior can increase an individual’s risk of developing conditions that may lead to cancer. For instance, having multiple sexual partners and engaging in skin-to-skin contact (unprotected intercourse) can lead to infection with the human papillomavirus (HPV) or the human immunodeficiency virus (HIV). HPV is a risk factor in reproductive cancers, especially cervical cancer in women. It also has been linked to some head and neck cancers, notably of the tonsils. HIV raises the risk of cervical cancer, vulvar cancer, anal cancer and lymphoma, and is believed to increase the risk of testicular and penile cancers. Individuals can therefore help prevent cancer by limiting their number of sexual partners and practicing safe sex. It is important to stress that condoms do not prevent the spread of disease in areas of the skin not covered by the condom. In 2006, the Food and Drug Administration approved the first vaccine that protects against four strains of HPV, two of which cause 70 percent of cervical cancer cases. The vaccine is approved for girls and women ages 9 to 26.

  • Fertility drugs/oral contraceptives. Studies regarding the relationship between fertility drugs and cancer are inconclusive. However, fertility drugs increase a woman’s ovulations as well as the levels of hormones related to ovulation, both of which are suspected to increase the risk of ovarian cancer. Additionally, the use of oral contraceptives (birth control pills) has been linked to an increased risk of cancer, particularly breast cancer. Women who take fertility drugs or oral contraceptives should discuss any concerns, recommendations for monitoring and possible alternatives with their physician.

  • Hormone replacement therapy (HRT). Women may be prescribed HRT to counter some of the symptoms and potential effects of menopause on the body. Though studies are inconclusive, it is suspected that a relationship exists between HRT and increased risk of some forms of cancer, such as breast cancer. However, HRT is also believed to reduce the risk of colorectal cancer and possibly other medical conditions, including osteoporosis and heart disease.  Women who take or plan on taking HRT should discuss their concerns and possible alternatives with their physician. A major report by the Women’s Health Initiative in 2002 indicated there were elevated risks of breast cancer for women who used HRT. Since that time, the level of HRT use has dropped precipitously.

  • Occupational exposures. Some individuals are exposed to carcinogens in the workplace, such as asbestos. Asbestos is a group of fibrous minerals that occurs naturally in the environment and can cause lung and other cancers, especially among people who also smoke. Miners and people in the shipbuilding industry, for instance, may be exposed to this chemical through inhalation of its fibers in the air. Another carcinogen that may affect workers is benzene, a colorless, flammable liquid that may be found in rubber factories and chemical plants. It also may be present in oil refineries and gasoline industries.  
    The Occupational Safety and Health Administration (OSHA) has implemented certain regulations regarding benzene in the workplace. To help prevent cancer from chemical exposure, individuals should use personal protective equipment, such as a respirator, in these industries.
  • Lead exposure. Lead is a metal that occurs naturally in small amounts in the earth. There is some evidence that this metal is carcinogenic. Individuals can help prevent cancer by implementing the following cautionary measures:
    • Avoiding lead exposure in the home by using lead–free ceramics, paint and other products and hiring a qualified contractor to remove leaded paint from the home. People who live in homes built before 1980 should determine if their home contains leaded paint.
    • Remove dust from windowsills, floors and other surfaces with detergent and water. Move playpens and cribs away from areas where paint is chipping or peeling. It is also important to assure that children do not remove chipped paint and place it in their mouths. Children are at risk for neurologic damage from lead.
    • People who live in buildings with old pipes or water heaters should use cold tap water for drinking and cooking.

  • Ionizing radiation. Radiation is energy emission from any source. Ionizing radiation, a type of high-frequency radiation, has been found to cause cancer in some individuals. People may be exposed to ionizing radiation through certain medical tests, such as x-rays. However, the radiation in medical tests is typically in very small amounts.  Radiation therapy,  on the other hand, is frequently used to treat some types of cancer and involves very high dosages. This treatment can sometimes promote the development of secondary cancers. For most patients, the benefits of radiation therapy outweigh the risks.

There has been a great deal of speculation that aspartame, an artificial sweetener used in many diet beverages, is carcinogenic. However, the Food and Drug Administration (FDA), World Heath Organization (WHO) and the Joint Expert Committee of Food Additives of the United Nations Food and Agricultural Organization have all concluded that aspartame does not cause cancer in the general population. Most health experts do not believe that limiting products containing aspartame will help prevent cancer.

There has also been much controversy about whether cellular phone use increases an individual’s cancer risk, especially brain cancer. Because cell phones are a fairly new technology, their impact on health is not yet fully understood. However, most cell phones produce low energy levels and do not emit ionizing radiation. This makes them an unlikely cause of cancer. Limiting cell phone use is not considered a preventive measure for brain tumors or other cancer. 

Environmental factors and cancer prevention

Environmental factors can also increase an individual’s cancer risk. These include:

  • Sunlight and ultraviolet (UV) light exposure. The sun provides warmth and light. However, it also produces UV radiation that can damage an individual’s eyes and skin – even on days that are overcast or cloudy. The two main types of UV rays are UVA and UVB rays. Both of these contribute to skin cancer, the most common type of cancer.

    To avoid becoming one of over a million individuals diagnosed with skin cancer in the United States each year, individuals should:
    • Limit direct exposure to the midday sun when the rays are the strongest

    • Wear clothing that protects as much of the body as possible

    • Wear a hat with a two- to three-inch brim to protect the head and neck

    • Use sunscreen with a Sun Protection Factor (SPF) of 15 or greater on all exposed skin, including the lips

    • Wear sunglasses that block 99 percent or more of harmful UV rays

    • Avoid indoor tanning booths and beds

    • Have the skin examined regularly by a dermatologist

  • Chemical exposure. Exposure to certain chemicals can also increase a person’s risk of developing cancer. One such chemical is benzene, a colorless, flammable liquid that has a sweet odor. Environmental sources of this volatile chemical include:
    • Gasoline
    • Automobile exhaust fumes
    • Cigarette smoke (including secondhand smoke)
    • Coke oven emissions
    • Waste water from some industries
    • Household products (e.g., some cleaning products, detergents and glues)

Workers in certain industries are also exposed to benzene, and small amounts of the chemical are found in drinking water. The Environmental Protection Agency (EPA) limits for benzene in the public water supply is 5 parts per billion.

Limiting exposure to benzene and other carcinogenic chemicals may reduce the risk of cancer. Therefore, people should exercise preventative measures such as avoiding secondhand smoke and closing car windows when driving in areas of heavy vehicular traffic (which have increased concentrations of benzene).

Sometimes the public becomes concerned about so-called environmental cancer risks that have not been proven, or situations in which exposures to known carcinogens are at levels so low they are considered negligible. According to the American Cancer Society (ACS), there is no evidence to support that cancer can be prevented by avoiding exposure to the following sources: 

  • Pesticides
  • Non-ionizing radiation
  • Toxic wastes
  • Nuclear power plants
  • Power lines
  • Cellular phone towers

Cancer screening and prevention

Sometimes cancer cannot be prevented because it is associated with an inherited trait, which means that a certain genetic mutation is passed down from generation to generation. About 10 percent of all cancers are linked to heredity. Some genetic tests are available to identify individuals who are more likely to develop certain cancers, and scientists are continuing to develop such tests.

Advanced age, another common cancer risk factor, also cannot be prevented. Additionally, some forms of cancer, such as breast, ovarian and endometrial cancer, may result from prolonged hormone production in the body (e.g., early menarche and late menopause) that cannot be regulated. 

Individuals with these and other increased cancer risks can, however, help prevent the development of cancer through regular self-examination and screenings. Physicians may recommend a more frequent cancer screening schedule or more detailed tests for high-risk individuals.

Regular cancer screenings can help detect precancers or cancers in their beginning stages, when they are most easily treated. Skin, oral, cervical and prostate cancers are examples of cancers that may be detected in precancerous stages. Identifying and treating cancers in these stages significantly increases a person’s chance of survival.

Cancer screenings should include the mouth, skin, and colon and rectum. Cancers in men that may be detected in self-examination or screening tests include prostate, penile, and testicular cancers.

In women, regular breast self-examinations may help to detect any changes that could indicate the need for medical attention. In addition, women should receive regular gynecological examinations including a Pap test to detect abnormalities of the cervix and mammograms for breast cancer detection.

For the first time, a general vaccine is available to prevent a type of cancer. In 2006, the Food and Drug Administration approved the first vaccine against several strains of the human papillomavirus (HPV), which causes most cases of cervical cancer and may be associated with some oral cancers. Normally, people may be infected with HPV during sexual contact, and the virus clears on its own. In some cases, it may contribute to cancer. The HPV vaccine prevents the virus from developing. The vaccine is approved for girls and women ages 9 to 26. Women who have received the vaccine should still receive regular Pap smears to monitor for HPV strains not covered by the vaccine.

Questions for your doctor about prevention

Preparing questions in advance can help patients have more meaningful discussions with their physicians regarding their conditions. Patients may wish to ask their doctor the following questions about cancer prevention:

  1. Which cancers do I have the greatest chance of developing?
  2. Do I have any medical conditions that place me at higher risk for cancer?
  3. Is there anything in my family history that increases my risk of cancer?
  4. Should I consider any genetic testing? If so, for which cancers?
  5. Which lifestyle habits should I change to reduce my risk of cancer?
  6. Which screening tests should I have and on what schedule?
  7. Do I take any medications that can increase my risk of cancer?
  8. Do you recommend any vitamin or herbal products that may help prevent cancer?
  9. Are there any preventive surgical procedures I should consider?
  10. Does my work environment present an increased risk for cancer?
  11. What self-examinations should I conduct to help prevent cancer?
  12. Are there ways I can help prevent cancer in my children?
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