While there are factors that can increase your risk of cancer, the majority of cancers occur in people who don't have any known risk factors.
Factors known to increase your risk of cancer include:
Age: While it's more common in older adults, cancer isn't exclusively an adult disease; cancer can be diagnosed at any age.
Habits: Certain lifestyle choices are known to increase your risk of cancer. Smoking, drinking more than one drink a day (for women) or two drinks a day (for men), excessive exposure to the sun or frequent blistering sunburns, and having unsafe sex can contribute to cancer.
Environment: The environment around you may contain harmful chemicals that can increase your risk of cancer. Chemicals in your home or work place, such as asbestos and benzene, also are associated with an increased risk of cancer.
Family history: Only about 10 percent of cancers are due to an inherited condition. If cancer is common in your family, it's possible that mutations are being passed from one generation to the next. Keep in mind that having an inherited genetic mutation doesn't necessarily mean you'll get cancer.
Health conditions: Some chronic health conditions can increase your risk of developing certain cancers. Talk to your doctor about your risk.
The American Cancer Society’s Cancer Facts & Figures for 2014 provides a concise summary of frequently used cancer statistics and information about major risk factors.