What are bone metastases?
Bone metastases are tumors that occur when cancer cells break away from the place where they started growing and move into bone tissue. Bone metastases are considered a form of advanced cancer. These secondary cancers within the bone are difficult to cure, but treatments are available to lessen the symptoms and lengthen life.
Bone metastases are common in many people with cancer. Bone metastases can sometimes result in severe pain and neurological impairment due to changes in your bone structure. Other symptoms of bone metastases can include:
- fragile bones
- high levels of calcium in the blood, which may cause nausea and confusion
- a loss of urinary or bowel control
- weakness in the legs
- a low blood cell count and anemia due to the loss of bone marrow
Metastatic cancer can severely damage your bones. Metastatic tumors can destroy your surrounding bone tissue, causing osteolytic bone destruction. Osteolytic damage occurs most often from tumors that originate in the:
Other damage can result when new bone is formed due to chemicals released by the tumor. This new bone may be weak and deformed. When this occurs, it’s known as osteoblastic, or bone formation, damage. This occurs in cancers that begin as prostate, bladder, or stomach cells. Some cancers, like breast cancer, can create both osteolytic and osteoblastic damage.
Both osteoblastic and osteolytic damage can cause pathological bone fractures. A pathological bone fracture is a fracture caused by a disease, as opposed to a traumatic fracture caused by external damage to your bone. Bones affected by this kind of damage break not from a fall or pressure, but during everyday activities. Damage to the bones of the spine can also affect the nerves of the spinal cord, causing neurological problems.
Bone metastases aren’t the same as bone cancer. Bone metastases are formed from cancerous cells that start elsewhere in your body. So, bone metastases could, for instance, be cancerous breast tissue, or another type of tissue somewhere in your body, that has started growing inside the bone tissue.
Cancer is a disease in which abnormal cells start dividing without control. Some tumors cells can break off and move around your body. Most of these shed cells die off, but some live on in new tissue and create a metastatic tumor. These metastases can remain hidden, even when the original tumor is gone and your doctor determines that you’re free of cancer.
It’s unclear why certain tumors become metastatic and others don’t. In certain types of cancer, such as advanced breast cancer or advanced prostate cancer, up to 70 percent of patients develop bone metastases.
The most common cancers that result in bone metastases include:
The most common locations for bone metastases include the:
Your doctor will perform a full medical history and physical exam, including a discussion of any past incidence of cancer. They can then order several tests, including:
- X-rays of the affected bone
- bone scans to see if other bones are affected
- CT scans
- MRI scans
- blood tests
If your doctor needs to determine whether the affected bone is the result of a bone metastasis or a primary bone cancer, they may perform a biopsy. During a biopsy, they’ll remove a small amount of the tumor and send it to a pathologist for a thorough examination.
Treatment of metastases often depends on the location and the source tumor cells. Treatments can include radiation, medication, and surgery.
Radiation therapy is often used to slow the growth of a bone metastasis. The types of radiation therapy include the following:
- Local field radiation involves your doctor directing radiation at the tumor and nearby tissue. It can completely relieve pain in 50–60 percent of cases.
- Hemi-body radiation involves your doctor directing radiation at a large part of your body. Your doctor can do this if you have multiple bone metastases.
- Radioisotope therapy involves your doctor injecting radioactive medication through your vein.
Medications are a key part of therapy for treating bone metastases. They may include one or more of the following:
- bone-building medications, such as bisphosphonates, to help reduce bone damage
- chemotherapy to kill tumor cells and reduce tumor size
- hormone therapy to slow certain hormones for cancers like breast cancer and prostate cancer
- pain medications
Surgery may be necessary when your bones have fractured or will soon fracture. Your doctor may remove tumors surgically. They may attach fixation devices directly to surrounding bone. They can use bone cement for reinforcing your bone structure.
Heating or freezing cancer cells with a probe, called radiofrequency ablation or cryoablation, can also reduce tumor size.
All of these treatment methods have risks. You and your doctor will arrive at a unique treatment for your specific cancer. You may work with a variety of doctors to tailor your care.
Bone metastases are a type of advanced cancer. It’s often not possible for doctors to remove all cancer cells. A wide variety of treatments are available to reduce the size of metastases and slow their growth. This can reduce pain and other symptoms, and it can improve quality of life and longevity.