What are the main risk factors for cancer?

The National Cancer Institute lists the most-studied known or suspected risk factors for cancer as:

• Age
• Alcohol
• Cancer-causing substances
• Chronic inflammation
• Diet
• Hormones
• Immunosuppression (a weakened immune system)
• Infectious agents
• Obesity
• Radiation
• Sunlight
• Tobacco

Some of these risk factors can be avoided, while others—such as growing older—cannot. Limiting your exposure to avoidable risk factors may lower your risk of developing certain cancers.

Cancer risk factors include exposure to chemicals or other substances as well as certain behaviors, and 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.

The National Cancer Institute has a detailed page for each of these risk factors. A healthcare team can help you understand which ones matter most for your situation.