Metastatic Cancer

Metastatic cancer is cancer that has spread from the part of the body where it started (called its primary site) to other parts of the body. When cells break away from a cancerous tumor, they can travel to other areas of the body through either the bloodstream or lymphatic channels.

When the cells travel through lymphatic channels they can become trapped in lymph nodes, often those closest to the cancer’s primary site. When the cells travel through the bloodstream they can go to any part of the body. Most of these cells die, but occasionally they don't. They settle in a new location, begin to grow, and form new tumors. The spread of a cancer to a new part of the body is called metastasis.

Even when cancer has spread to a new location, it is still named after the part of the body where it started. For example, if prostate cancer spreads to the bones, it is still called prostate cancer, and if breast cancer spreads to the lungs it is still breast cancer. A person with breast cancer that has spread to the bones is said to have breast cancer with bone metastases. (If you are talking about more than one metastasis, they are called metastases.)

When cancer comes back in a patient who appeared to be free of cancer (in remission) after treatment, it is called a recurrence. Cancer may recur in several ways: 

• local recurrence (in or near the same organ where it developed), for example, a recurrence of breast cancer in the skin of the chest near where the original cancer was removed; 
• regional recurrence (in nearby lymph nodes or in the area from which lymph nodes had been removed); or 
• distant recurrence (involving any other part of the body not included in local or regional recurrence). Distant recurrence is also called metastatic recurrence. For example, the cancer might recur in distant parts of body such as in bones, the liver, or the lungs. This happens because some cancer cells have broken off from the original tumor, traveled elsewhere, and begun growing in these new places.

Sometimes metastatic tumors have already developed when the cancer is first diagnosed. In some cases, the metastasis is discovered before the primary (original) tumor is found. Sometimes a cancer can spread widely throughout the body before it is discovered without developing as a large tumor in the site where it started. When the original site cannot be determined, this condition is called cancer of unknown primary.

Bone Metastasis: What It Means

Cancer cells that break off from a primary tumor and enter the bloodstream can reach nearly all tissues of the body. Bones are one of the most common sites for these circulating cells to settle and start growing. Metastases can occur in bones anywhere in the body, but they are mostly found in bones near the center of the body.

Bone metastasis is not the same as cancer that starts in the bone, which is called primary bone cancer. Bone metastasis and primary bone cancers are very different. Primary bone cancer is much less common than bone metastasis.

Bone metastasis is one of the most frequent causes of pain in people with cancer. It can also cause bones to break and high calcium levels in the blood (calcium is released from damaged bones). Bone metastasis also causes other symptoms and complications that can lower your ability to maintain your usual activities and lifestyle.

Bone metastases develop in many people with cancer (except for those with skin cancers such as basal cell and squamous cell cancer) at some point in the course of the disease. The bone is the third most common site for metastases after lung and liver.

The spine is the part of the skeleton most commonly affected by bone metastasis. The next most common parts are the pelvis, hip, upper leg bones (femurs), and the skull.