Risk Factors

Cancer can be caused by external factors, internal factors, or lifestyle factors.  The most common risk factors for cancer are:


Sunlight and other Ionizing radiation:  Ultraviolet (UV) radiation from the sun, sunlamps, and tanning booths can increase one’s risk for skin cancer.  Ionizing radiation comes not only from the sun and outer space, but also from radioactive fallout, radon gas, x-rays, and other sources.  People exposed to radioactive fallout or radon from working in mines, or radiation as used in medical x-ray machines and radiation therapy are at an increased risk.

Certain chemicals and other substances:  People with certain jobs (e.g., painters, construction workers, chemical industry workers) have an increased risk of cancer as a result of exposure to chemicals used in these industries such as asbestos, benzene, benzidine, cadmium, nickel, or vinyl chloride are known to increase the risk of cancers.

Some viruses and bacteria:  Infections caused by certain viruses or bacteria may increase the risk of cancer.  These include Human papillomaviruses (HPVs), Hepatitis B and Hepatitis C viruses, Human T-cell leukemia/lymphoma virus (HTLV-1), Human immunodeficiency virus (HIV), Epstein-Barr virus (EBV), Human herpesvirus 8 (HHV8), and Helicobacter pylori.


Aging:  Most cancers occur in people over the age of 65.

Certain hormones:  Hormone therapy can increase the risk of breast cancer, and a number of other cardiovascular complications.

Family history of cancer:  Some genetic mutations that increase one’s risk for cancer may be inherited from one’s parents.  Certain types of cancers including melanoma and cancers of the breast, ovary, prostate, and colon sometimes run in families.  Most often, an inherited gene increases one’s risk of developing cancer, with environmental factors determining whether or not cancer manifests in a particular individual.  Individuals with a family history may still be able to adequately protect themselves by eliminating environmental risk factors for cancer, and receiving routine preventive care.


Alcohol:  Drinking more than two drinks per day for several years may increase the risk for cancers of the mouth, throat, esophagus, larynx, liver, and breast.  The risk increases with the amount of alcohol that a person drinks.

Poor diet, physical inactivity, or being overweight:  Consuming a poor diet, lacking in physical activity, and overweight/obesity are risk factors for cancer.

Tobacco Use:  Using tobacco or exposure to secondhand smoke increases one’s risk for cancer.  Smokers are at a higher risk of developing lung, larynx (voice box), mouth, esophagus, bladder, kidney, throat, stomach, pancreatic, and cervical cancers.  They also are more likely to develop acute myeloid leukemia.


A substantial proportion of cancers can be prevented, including all cancers caused by tobacco use and heavy alcohol consumption.  In 2017, about 190,500 of the estimated 600,920 cancer deaths in the US will be caused by cigarette smoking.  In addition, the World Cancer Research Fund estimates that 20% of all cancer diagnosed in the US are caused by excessive body weight, physical inactivity, excess alcohol consumption, and poor nutrition.  Take these steps to reduce your risk and protect yourself from cancer:

Quit Smoking.  Quit using all types of tobacco, including smokeless tobacco. Call or text the Hawaii Tobacco QuitLine to receive free quit support and nicotine replacement therapy.

Limit Exposure to Sunlight and other Ionizing radiation.  Avoid midday sun, wear long sleeves, long pants, a wide-brimmed hat, and sunglasses with UV absorbing lenses, use sunscreen, and stay away from sunlamps and tanning booths.

Handle chemicals and other substances with care.  It is important to use precautions while handling pesticides, used engine oil, paint, solvents, and other chemicals.

Protect yourself from viruses and bacteria.  Protections from cancers caused by infections includes obtaining recommended vaccinations, using protection during sex, not sharing needles, and in the case of H. Pylori, receiving adequate treatment for a stomach ulcer caused by this bacterium.

Limit alcohol consumption.  Limit alcohol intake to no more than two drinks per day for men and 1 drink a day for women.

Practice eating healthy and exercising.  Eat a diet rich in fruits and vegetables, be physically active, and maintain a healthy weight.