Bone tissue undergoes constant remodeling throughout life. Specialized cells continually deposit new bone tissue, while other cells break down and resorb old tissue. The balance between bone deposition and breakdown is tightly regulated and determines bone density. Bone cancer develops when the bone-depositing or resorbing cells begin to proliferate out of control, leading to the development of tumor growths on bone tissue. In its advanced stages, bone cancer cells gain the ability to metastasize and travel throughout the body to form cancerous growths in distant tissues. Patients with metastatic bone cancer may suffer from a range of symptoms.
Bone Fractures
In the late stages of bone cancer, affected bones become vulnerable to fracture, according to the University of Maryland Medical Center. Osteolytic bone cancers--cancers that originate from the cells that break down bone tissue--commonly lead to weakened bones that fracture easily. Cells in osteolytic cancers begin to resorb bone tissue at a much greater rate than new bone is deposited. The result is a decrease in bone density, with bone tissue eaten away at the site of tumor growth. Patients with extensive bone cancer must be extremely careful during any physical activity to avoid injury. In some cases, metastatic bone cancer patients may receive medication to help slow the breakdown of bone tissue.
Difficulty Breathing
Metastatic bone cancers, such as Ewing's sarcoma, commonly metastasize to the lungs, according to Children's Hospital Boston. During metastasis, the bone cancer cells colonize within lung tissue and begin to attack healthy lung cells to facilitate tumor growth. As the cancer progresses, the resulting tumor occupies more and more space in the lungs, decreasing lung capacity and blocking airways within the lung. As a result, patients with metastatic bone cancer that has metastasized to the lungs often experience difficulty breathing and shortness of breath. Bone cancer patients with this sort of metastasis may also suffer from chronic coughs and cough up bloody sputum. Extensive cancer growth within the lung may be treated with radiation or surgery to remove clusters of tumors and increase the patient's quality of life.
Abnormal Blood Cells
Some bone cancers also spread into the bone marrow, according to Brigham and Women's Hospital. Bone marrow contains populations of stem cells that develop into blood cells. The stem cells interact with other factors within the bone marrow and mature into red blood cells, white blood cells or platelets. During bone cancer metastasis, stem cells within the bone marrow become disrupted by cancer growth and cannot properly mature into functional blood cells. As a result, patients with metastatic bone cancer often have abnormal or dysfunctional blood cells. If left untreated, blood cell deficiencies can lead to diseases like anemia or may lead to an immunodeficiency that leaves a patient vulnerable to infection. Patients with severe blood abnormalities as a result of bone cancer may receive bone marrow or blood transfusions to provide functioning blood cells.
