Definition of Lung Cancer with Bone Metastases
Lung cancer with bone metastases refers to lung cancer cells that spread to bone either through the bloodstream or through the lymphatics (vessels that carry infection-fighting cells through the body). Cancer metastatic to bone is different than bone cancer – cancers that originate in the bones and are made up of abnormal bone cells. Cancer metastatic to bone is made up of cells that originate in the primary cancer -- in this case, the lungs.
Lung cancer is the third most common form of cancer to spread to bone, and when metastatic bone cancer is found without an obvious source, half of the time it is related to an underlying lung cancer. Bones that lung cancer often spreads to include the spine (especially vertebrae in the chest and lower abdominal areas), the pelvis, and the upper bones of the arm and leg (the humerus and femur). Lung cancer is also somewhat unique in that it can spread to bones in the hands and feet.
Pain is usually the first symptom of lung cancer with bone metastases. The pain may initially feel like a muscle pull or strain, but gradually worsens and can become severe. When bone metastases involve the arms and legs, pain is often worse with movement. Pain due to spread of lung cancer to the spine is often worse at night and after resting in bed.
If bone metastases involve the spine, compression of the spinal cord due to the tumor may cause pain with walking and weakness or tingling in the legs.
Sometimes, the first symptom that lung cancer has spread to bone is a fracture (pathological fracture). In this setting, cancer cells replace normal bone tissue, weakening it so it is more likely to break. These fractures may occur without any significant trauma and during normal daily activities.
Due to breakdown of bone, which releases calcium, an elevated level of calcium in the blood (hypercalcemia) may cause confusion, nausea and vomiting, thirst, and muscle weakness.
Tests that are used to look for bone metastases may include:
- Bone scans: Bone scans are used less frequently to look for bone metastases than in the past, and it can sometimes be difficult to distinguish cancer from other bone conditions.
- PET Scans: PET scans are very sensitive for detecting bone metastases, as they look for areas of active tumor growth in bone.
- MRI Scans
- CT Scans
Treatment for lung cancer with bone metastases is primarily palliative -– that is, it is meant to relieve symptoms, but not cure the cancer. The primary goal of treatment is to reduce pain caused by the metastases, and to treat or prevent fractures. Treatment may include:
Radiation Therapy - Radiation is the most common treatment used to lessen pain, prevent fractures, and relieve spinal cord compression from bone metastases. Most people get substantial pain relief from radiation therapy, and for many people, radiation can relieve their pain completely.
Surgery - Surgery is used primarily to stabilize bones if they fracture, or to prevent a fracture in a bone that is very weakened by cancer (impending fracture). Surgery may sometimes be used if the tumor is causing significant pressure on the spinal cord.
Bisphosphonates - Bisphosphonates are medications that have been used to treat osteoporosis (thin bones), but may also help to prevent the breakdown of bone in people with bone metastases due to cancer. An example of a bisphosphonate that is sometimes used with lung cancer is zoledronic acid (Zometa).
These medications are given through a vein every 3 to 4 weeks. While they are relatively safe, in rare instances they can cause a complication known as osteonecrosis of the jaw (the breakdown of bone in the jaw) and kidney damage.
Researchers are also looking at complementary methods of treating bone pain due to metastatic cancer, and acupunture may hold promise when used in addition to these other treatments. Clinical trials are in progress looking at better ways to treat bone metastases due to cancer.
PrognosisThe median survival –- that is, the amount of time after which 50% of people are alive and 50% have passed away -- is sadly less than 6 months. Survival is somewhat higher for women, those with adenocarcinoma, people with only one bone metastasis, and individuals who do not have any fractures. That said, some people have survived and done well for many years following a diagnosis of lung cancer with bone metastases.
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