A risk factor is anything that affects your chance of getting a disease such as cancer. Different cancers have different risk factors. For example, unprotected exposure to strong sunlight is a risk factor for skin cancer. Smoking is a risk factor for cancer of the lung and many other cancers. Since a person must have cancer to have metastases, the risk factors for metastatic cancer are the same as those for cancer in general. For many cancers, risk may be affected by some factors that you can't control, such as age or ethnicity. It is more helpful to focus on those that you can control, such as smoking or diet.

These are the most significant lifestyle risk factors, over which you have some control:

• tobacco use
• an unhealthy diet
• not getting enough physical activity
• obesity
• alcohol abuse

Together, these factors are responsible for about 2 out of 3 fatal cancers. Genetic risk factors (inheriting certain genes that increase cancer risk) only account for 5% to 10% of cancers. About 6% of deaths from cancers result from being exposed to cancer-causing substances in the workplace and pollutants in the environment. If you want more information on causes of cancer, please see our information on each specific type of cancer.

Risk factors for bone metastases

Some people with cancer develop bone metastases and others do not. Doctors still don't know enough to predict for certain who will develop bone metastases over time. But they do know that certain kinds of cancer are more likely to spread to bones (see the section "Key statistics"). Among people with the same kind of cancer, tumors that are larger and have already spread to lymph nodes are generally more likely to spread to bone. For some kinds of cancer, a high grade (the cancer cells look very abnormal under a microscope) and certain genetic changes make the cancer cells more likely to spread to bones.

This brings up one important difference in your risk of getting cancer and your risk of bone metastases. Having a cancer that is detected after it has spread to other organs raises your risk of bone metastases. Finding cancer early often means it has not yet had a chance to spread. This can give a person a better chance of successful treatment and a lower risk of future metastases.

Last Medical Review: 01/13/2008
Last Revised: 05/13/2009