Cancer has been the worst nightmares that have occurred to many families once one of their members has been diagnosed positive with the disease. In fact, many families in France have been seeking help form NGOs and government institutions to settle medical bills emanating from cancer treatment. It is usually not possible to know exactly why one person develops cancer and another doesn’t. But research has shown that certain risk factors may increase a person’s chances of developing cancer. There are also factors that are linked to a lower risk of cancer. These are sometimes called protective risk factors, or just protective factors. Cancer risk factors include exposure to chemicals or other substances, as well as certain behaviors. They also include things people cannot control, like age and family history. A family history of certain cancers can be a sign of a possible inherited cancer syndrome.
Most cancer risk and protective factors are initially identified in epidemiology studies. In these studies, scientists look at large groups of people and compare those who develop cancer with those who don’t. These studies may show that the people who develop cancer are more or less likely to behave in certain ways or to be exposed to certain substances than those who do not develop cancer. Such studies, on their own, cannot prove that a behavior or substance causes cancer. For example, the finding could be a result of chance, or the true risk factor could be something other than the suspected risk factor. But findings of this type sometimes get attention in the media, and this can lead to wrong ideas about how cancer starts and spreads. When many studies all point to a similar association between a potential risk factor and an increased risk of cancer, and when a possible mechanism exists that could explain how the risk factor could actually cause cancer, scientists can be more confident about the relationship between the two. The list below includes the most-studied known or suspected risk factors for cancer. Although some of these risk factors can be avoided, others such as growing older cannot. Limiting your exposure to avoidable risk factors may lower your risk of developing certain cancers.
Age and Cancer Risk
Advancing age is the most important risk factor for cancer overall, and for many individual cancer types. According to the most recent statistical data from the government of France and other relevant medical and healthy regulatory bodies, the median age of a cancer diagnosis is 66 years. This means that half of cancer cases occur in people below this age and half in people above this age. One-quarter of new cancer cases are diagnosed in people aged 65 to 74. A similar pattern is seen for many common cancer types. For example, the median age at diagnosis is 61 years for breast cancer, 68 years for colorectal cancer, 70 years for lung cancer, and 66 years for prostate cancer. But the disease can occur at any age. For example, bone cancer is most frequently diagnosed among people under age 20, with more than one-fourth of cases occurring in this age group. And 10 percent of leukemia are diagnosed in children and adolescents under 20 years of age, whereas only 1 percent of cancer overall is diagnosed in that age group. Some types of cancer, such as neuro-blastoma, are more common in children or adolescents than in adults.
Many people who receive organ transplants take medications to suppress the immune system so the body won’t reject the organ. These “immunosuppressive” drugs make the immune system less able to detect and destroy cancer cells or fight off infections that cause cancer. Infection with HIV also weakens the immune system and increases the risk of certain cancers. Research has shown that transplant recipients are at increased risk of a large number of different cancers. Some of these cancers can be caused by infectious agents, whereas others are not. The four most common cancers among transplant recipients and that occur more commonly in these individuals than in the general population are Non-Hodgkin lymphoma (NHL) and cancers of the lung, kidney, and liver. NHL can be caused by Epstein-Barr Virus EBV infection, and liver cancer by chronic infection with the hepatitis B (HBV) and hepatitis C HVC viruses. Lung and kidney cancers are not generally thought to be associated with infection. People with HIV/AIDS also have increased risks of cancers that are caused by infectious agents, including EBV; human herpes virus 8 or Kaposi sarcoma-associated virus; HBV and HCV, which cause liver cancer; and human Papilloma virus, which causes cervical, anal, oropharyngeal, and other cancers. HIV infection is also associated with increased risks of cancers that are not thought to be caused by infectious agents, such as lung cancer.
People who are obese may have an increased risk of several types of cancer, including cancers of the breast (in women who have been through menopause), colon, rectum, endometrium (lining of the uterus), esophagus, kidney, pancreas, and gallbladder. Conversely, eating a healthy diet, being physically active and keeping a healthy weight may help reduce risk of some cancers. These healthy behaviors are also important to lessen the risk of other illnesses, such as heart disease, type II diabetes, and high blood pressure.
Tobacco use is a leading cause of cancer and of death from cancer. People who use tobacco products or who are regularly around environmental tobacco smoke (also called secondhand smoke) have an increased risk of cancer because tobacco products and secondhand smoke have many chemicals that damage DNA. Tobacco use causes many types of cancer, including cancer of the lung, larynx (voice box), mouth, esophagus, throat, bladder, kidney, liver, stomach, pancreas, colon and rectum, and cervix, as well as acute myeloid leukemia. People who use smokeless tobacco (snuff or chewing tobacco) have increased risks of cancers of the mouth, esophagus, and pancreas. There is no safe level of tobacco use. People who use any type of tobacco product are strongly urged to quit. People who quit smoking, regardless of their age, have substantial gains in life expectancy compared with those who continue to smoke. Also, quitting smoking at the time of a cancer diagnosis reduces the risk of death.
Inflammation is a normal physiological response that causes injured tissue to heal. An inflammatory process starts when chemicals are released by the damaged tissue. In response, white blood cells make substances that cause cells to divide and grow to rebuild tissue to help repair the injury. Once the wound is healed, the inflammatory process ends. In chronic inflammation, the inflammatory process may begin even if there is no injury, and it does not end when it should. Why the inflammation continues is not always known. Chronic inflammation may be caused by infections that don’t go away, abnormal immune reactions to normal tissues, or conditions such as obesity. Over time, chronic inflammation can cause DNA damage and lead to cancer. For example, people with chronic inflammatory bowel diseases, such as ulcerative colitis and Crohn have an increased risk of colon cancer.
Cancer-Causing Substances in the Environment
Cancer is caused by changes to certain genes that alter the way our cells function. Some of these genetic changes occur naturally when DNA is replicated during the process of cell division. But others are the result of environmental exposures that damage DNA. These exposures may include substances, such as the chemicals in tobacco smoke, or radiation, such as ultraviolet rays from the sun. People can avoid some cancer-causing exposures, such as tobacco smoke and the sun’s rays. But others are harder to avoid, especially if they are in the air we breathe, the water we drink, the food we eat, or the materials we use to do our jobs. Scientists are studying which exposures may cause or contribute to the development of cancer. Understanding which exposures are harmful, and where they are found, may help people to avoid them. The substances listed below are among the most likely carcinogens to affect human health. Simply because a substance has been designated as a carcinogen, however, does not mean that the substance will necessarily cause cancer. Many factors influence whether a person exposed to a carcinogen will develop cancer, including the amount and duration of the exposure and the individual’s genetic background.
Radiation of certain wavelengths, called ionizing radiation has enough energy to damage DNA and cause cancer. Ionizing radiation includes radon, x-rays, gamma rays, and other forms of high-energy radiation. Lower-energy, non-ionizing forms of radiation, such as visible light and the energy from cell phones and electromagnetic fields, do not damage DNA and have not been found to cause cancer.
Radon is a radioactive gas given off by rocks and soil. Radon is formed when the radioactive element radium breaks down. Radium in turn is formed when the radioactive elements uranium and thorium break down. People who are exposed to high levels of radon have an increased risk of lung cancer. If you live in an area of the country that has high levels of radon in its rocks and soil, you may wish to test your home for this gas. Home radon tests are easy to use and do not cost much. Most hardware stores sell test kits. There are many ways to lessen the amount of radon in a home to a safe level.
X-Rays and Other Sources of Radiation
High-energy radiation, such as x-rays, gamma rays, alpha particles, beta particles, and neutrons, can damage DNA and cause cancer. These forms of radiation can be released in accidents at nuclear power plants and when atomic weapons are made, tested, or used. Certain medical procedures, such as chest x-rays, computed tomography (CT) scans Positron emission tomography (PET) scans and radiation therapy can also cause cell damage that leads to cancer. However, the risks of cancer from these medical procedures are very small, and the benefit from having them is almost always greater than the risks. Talk with your doctor if you think you may be at risk for cancer because you were exposed to radiation. People considering CT scans should talk with their doctors about whether the procedure is necessary for them and about its risks and benefits. Cancer patients may want to talk with their doctors about how radiation treatment could increase their risk for a second cancer later on.
The sun, sunlamps, and tanning booths all give off ultraviolet (UV) radiation. Exposure to UV radiation causes early aging of the skin and skin damage that can lead to skin cancer. People of all ages and skin tones should limit the amount of time they spend in the sun, especially between mid-morning and late afternoon, and avoid other sources of UV radiation, such as tanning beds. It is important to keep in mind that UV radiation is reflected by sand, water, snow, and ice and can go through windshields and windows. Even though skin cancer is more common among people with a light skin tone, people of all skin tones can develop skin cancer, including those with dark skin.
Follow these tips to protect your skin from sunlight:
- Wear a hat with a wide brim all around that shades your face, neck, and ears. Baseball caps and some sun visors protect only parts of your skin.
- Wear sunglasses that block UV radiation to protect the skin around your eyes.
- Wear long sleeves and long pants. Tightly woven, dark fabrics are best. Some fabrics are rated with an ultraviolet protection factor (UPF). The higher the rating, the greater the protection from sunlight.
- Use sunscreen products with a sun protection factor (SPF) of at least 15. Some doctors suggest using a product with an SPF of at least 30. Apply the product’s recommended amount to uncovered skin 30 minutes before going outside, and apply again every two hours or after swimming or sweating. Stay safe! Cancer is kills, however, it can be treated if noticed in its early stages.