The risk factors associated with metastatic cancer are the same as those of any cancer. Genetic risk factors account for between 5 percent and 10 percent of all cancers, according to the American Cancer Society (ACS). The bulk of cancers are caused instead by factors related to lifestyle or the environment. These include:

• Tobacco use
• Unhealthy diet
• Lack of exercise
• Alcohol abuse
• Radiation
• Infectious agents such as certain viruses
• Toxic chemicals or other environmental factors

Some types of primary cancers are especially prone to metastasizing to specific areas of the body. These include the following:

The risk of metastasis in an organ can sometimes depend on the specific type of cancer that is present. For example, squamous cell and basal cell skin cancers rarely spread. On the other hand, malignant melanoma skin cancers are more likely to spread to the lymph nodes, lungs, liver, brain and other organs.

In addition, most cancer cells that break free of a tumor are trapped in the next “downstream” capillary bed or set of lymph nodes. This is why metastatic cancers usually appear near the original cancer site. In addition, cancers frequently spread to the lungs because the heart pumps blood from all parts of the body through the lung’s blood vessels. The liver is also a common site of metastasis because cancers in the stomach and intestines are carried through blood to the liver.