Bone metastasis occurs when cancer in another part of the body spreads to the bone. It is one of the most frequent causes of cancer pain. It is different from primary bone cancer, which originates in the bone. When one tumor spreads, it is called a metastasis; when more than one spread, they are called metastases.This condition occurs in about half of all cancer cases, except skin cancer. Breast, lung and prostate cancer are the most frequent causes.
Cancer cells can spread, through the bloodstream, from the original location, and take up residence in almost any part of the body. Bones are one of the most common sites where this occurs. It can occur near the original cancer or far from it. The spine is affected most often, followed by the pelvis, hip, upper leg bones and skull.
The metastasis is the same type of tumor as the original cancer; it does not take on the characteristics of the new site.
Lung tumors that have spread to bone are the most dangerous form of bone metastases; patients with this condition have median survival rates of less than six months. Patients with breast and prostate cancer, however, have much better chances of survival.
