Metastatic cancer is cancer that has spread from its original site in the body to other parts of the body. It occurs when cells break free from a tumor and travel to other locations. These cells often form “colony” tumors and continue to grow in the new location. When cancer has spread to other tissues, it is known as metastasis.

Metastatic cancer should not be confused with cancer that has spread locally. Cancers that spread locally are found in nearby organs and tissues. For example, a tumor in the mouth may spread into the throat. With distant metastatic cancer, the disease spreads through the bloodstream or lymphatic system to other parts of the body.

In addition, metastatic cancer is not always the same as advanced cancer. An individual may be diagnosed with metastatic cancer even if only a small number of cells have spread. Minimally spread cancer may be treated successfully. However, if metastatic cancer has significantly invaded tissues and organs causing damage, it may advanced cancer.

Risk factors associated with metastatic cancer are the same as those for cancer in general. Lifestyle factors that can increase the risk of cancer include tobacco use, alcohol abuse, too little exercise and unhealthy diet. These factors contribute to the development of approximately two-thirds of all fatal cancers. Certain inherited genes also can increase a person’s risk for some cancers. The most common sites of metastasis include the bones, lungs, liver and brain.

Metastases are responsible for the majority of cancer-related deaths, according to the American Cancer Society (ACS). With the exception of non-melanoma skin cancer, about one-third of patients have metastasis at the time of their cancer diagnosis.

A great deal of research is devoted to the prevention of cancer metastasis. Currently, the only way to prevent cancer from spreading is early detection and effective treatment of the primary disease. There are a number of screening tests that can help detect early cancers, such as prostate, breast and colon cancer. These tests, however, cannot find all cancers and some may not be detected until after they have metastasized. In addition, there are some cancers that cannot be detected reliably with screening methods.