About secondary bone cancer

This section helps you understand more about secondary bone cancer – cancer that has spread to the bone from another part of the body. It includes general information about how secondary bone cancer is diagnosed and treated.

Learn more about:

• What is secondary bone cancer?
• Which cancers spread to the bone?
• The bones
• What types are there?
• Who gets secondary bone cancer?
• What are the causes?

What is secondary bone cancer?

Bone cancer can be either a primary or secondary cancer. Primary bone cancer means the cancer first started in the bone. It is a rare cancer.

Secondary bone cancer means that the cancer started in another part of the body, and has now spread (metastasised) to the bone. The 2 types of bone cancer are different, and this fact sheet is only about secondary bone cancer.

Secondary cancer in the bone, also called bone metastases or bone mets, often keeps the name of the original cancer. For example, breast cancer that has spread to the bone may be called secondary or metastatic breast cancer. Because the cancer has spread, it is considered advanced or stage 4 cancer. You may find it useful to look at information about the primary cancer type.

Cancer cells can spread from the original cancer (the primary cancer), through the bloodstream or lymph vessels, to any of the bones in the body.

Bones commonly affected by secondary bone cancer include the spine, ribs, pelvis, and upper bones of the arms (humerus) and legs (femur).

Which cancers spread to the bone?

Any type of cancer can spread to the bone.

The cancers most likely to spread to the bone include:

• prostate cancer
• breast cancer
• lung cancer
• kidney cancer
• thyroid cancer
• myeloma (a type of blood cancer)
• melanoma.

The bones

Bones have a number of important functions. These include:

• supporting the body
• protecting internal organs
• attaching to muscles to allow movement
• containing bone marrow, which stores and produces new blood cells
• storing proteins, minerals and nutrients, such as calcium.

Bones are made up of different parts, including a hard, outer layer (known as cortical or compact bone) and a spongy inner core (known as trabecular or cancellous bone). Bone marrow – a substance containing fat and blood stem cells that can become red blood cells, white blood cells, or platelets – is found in this spongy core.

Normal bone is constantly going through a process called remodelling, or turnover, in which old bone is broken down and replaced with new bone.

Bones of the body

Cancer can spread to any bone in the body. Bones commonly affected include the spine, ribs, pelvis and upper bones of the arms and legs.

Body structure

Bones are made up of a hard outer layer, an inner core, and spongy bone marrow found in this inner core. Cartilage is the tough material at the end of each bone that allows one bone to move against another at a joint.

What types of secondary bone cancer are there?

There are two main types of secondary bone cancer:

• Osteolytic – is where bone is broken down by the cancer cells without being replaced by new bone. Holes, also called lytic lesions, might form in the bone, which increases the risk of a break or fracture.
• Osteoblastic – is where new bone cells form abnormally in some areas. These areas are called osteoblastic (or sclerotic) lesions and even though they are very hard (dense), they make the bone weak and deformed.

Most people with secondary bone cancer develop either osteolytic or osteoblastic changes, but some have both.

Who gets secondary bone cancer?

Secondary bone cancer is much more common than primary bone cancer in Australia. It is more common in adults than children. The bone is one of the most common places cancer may spread to, along with the lymph nodes, liver, lungs and brain.

What are the causes?

Secondary bone cancer is always caused by cancer cells that have spread to the bone from a primary cancer elsewhere in the body. It isn’t fully understood why some people develop secondary bone cancer and others don’t.

→ READ MORE: Symptoms of secondary bone cancer