Doctors often can't explain why one person develops cancer and another doesn't. One reason may be that, over time, several factors may act together to cause normal cells to change and become cancerous.
The National Cancer Institute (NCI) and other cancer experts have found that certain risk factors increase the chance that a person will develop cancer. Many of these factors, such as smoking or eating an unhealthy diet, can be avoided. Others, such as family history and aging, can't, but everyone can benefit by avoiding known cancer risks.
According to the NCI, these are the most common cancer risk factors:
Too much exposure to the sun and sunlamps
An unhealthy diet
Lack of exercise
Excessive alcohol consumption
Exposure to carcinogenic chemicals and substances, such as benzene or vinyl chloride
Family history of cancer
Viruses, such as the human papillomavirus
Exposure to radiation
It's important to realize that having one or more risk factors doesn't mean you'll get cancer, the NCI says. It simply means you may be more likely to develop cancer than someone without those risk factors. Here are the risk factors according to what you can change and what you can't:
Behavioral risk factors. These are things you can change, such as smoking, an unhealthy diet, and lack of exercise.
Environmental risk factors. These are things found in your environment, such as secondhand smoke, asbestos, radon, UV radiation from the sun, and carcinogenic chemicals. You can take steps to avoid them.
Biological risk factors. These are physical characteristics that you can't change, such as gender, advancing age, and ethnic background. For instance, only men can get prostate cancer and only women can get ovarian cancer.
Genetic risk factors. Certain genes inherited from your parents can raise your risk. You may be at increased risk for cancer if another family member was diagnosed at a young age, if three or more generations have been diagnosed with similar cancers, or if three or more people have been diagnosed on the same side of the family.
If you are concerned about your cancer risk, talk with your health care provider about your risk and how to reduce it. He or she can also schedule cancer screening tests at appropriate times.