Cancer that has developed in one area of the body can spread beyond that site and invade other parts of the body. This process is called metastasis. The bone is a common site of metastasis for a number of different cancers. They include: lung, breast, prostate, kidney, thyroid cancers and multiple myeloma.

Cancer cells that have metastasized to the bone can damage the bone, which gives rise to symptoms. Various cancer treatments are available to control the symptoms and the spread of bone metastases or "bone mets".

Bone Basics

Bone is a type of connective tissue made up of minerals, such as calcium and phosphate, and the protein collagen. The outer layer of bone is called the cortex and the spongy center of bone is called cancellous bone. The bone marrow fills in the spaces within the spongy bone. Bone tissue is porous and alive, with blood vessels running through it.

Bone constantly repairs and renews itself through a process called remodeling. Two kinds of cells are involved:

• Osteoblasts, bone-forming cells
• Osteoclasts, cells that break down, or resorb, bone

Bones carry out a number of functions in the body.

• The skeleton provides structural support for the body.
• Bones store and release minerals that the body needs to function, such as calcium, magnesium, phosporus, and sodium when the body needs them.
• Bone marrow produces and stores blood cells--red blood cells that transport oxygen from the lungs to the rest of the body; white blood cells that fight infections; and platelets that help the blood clot.

When cancer cells invade the bone, any of these functions may be affected.

‹ previous section | next section ›