What is bone metastasis?
When cancer spreads from the part of the body where it started (its primary site) to other parts of the body it is called metastasis.
Metastasis can occur when cells break away from a cancerous tumor and travel through the bloodstream or through lymph vessels to other areas of the body. (Lymph vessels are much like blood vessels, except they carry a clear fluid called lymph back toward the heart.) Cancer cells that travel through the blood or lymph vessels can spread to other organs or tissues in distant parts of the body.
Many of the cancer cells that break off from the original tumor die without causing any problems. But some settle in a new area. There, they begin to grow and form new tumors. When cancer spreads, we say that it metastasizes. If there is only a single tumor, it’s called a metastasis or a metastatic tumor. When there are 2 or more metastatic tumors, it’s called metastases.
Sometimes metastatic tumors are found by tests done when the primary cancer is first diagnosed. In other cases, the metastasis is found first, causing the doctor to look for the place that the cancer started.
Sometimes, no metastases are seen when the cancer is first found. Instead, they are found later, after the patient has been treated and was thought to be cancer free. When a cancer has come back after treatment, it’s called recurrence. Recurrence is not the same as metastases – it can also occur at or near the place the cancer started. When it does come back as metastases, it’s called a distant recurrence. For a cancer to recur as metastatic disease, some cancer cells had to have broken off from the primary tumor and survived the initial treatment. These cells traveled through the body and started growing in new places.
Different cancers tend to spread to different sites, but some of the most common sites of distant recurrence include the bones, liver, brain, and lungs.