Bone tissue growth and remodeling begins in utero and continues throughout a person's life. Specialized cells called osteoblasts continuously deposit new bone tissue, while other cells called osteoclasts breast down old tissue. The balance between bone growth and reabsorption helps maintain normal bone mass. Primary bone cancer develops when the balance between these two processes becomes disrupted, leading to abnormal cell growth on the bone. In the last stages of bone cancer, cancer cells begin to metastasize and form tumors in distant organs. In the late stages of bone cancer, patients experience a number of symptoms due to extensive cancer growth.
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A very common symptom of later-stage bone cancer is excessive bone weakness. This is because the abnormal growth of bone cancer cells weakens the integrity of the bone tissue. Some types of bone tumors, called osteolytic tumors, also directly overactivate osteoclastic activity, leading to an excessive breakdown of bone tissue without sufficient new bone deposition, according to BoneTumor.org. As a result, patients with osteolytic bone cancers develop excessive bone weakness and bone wasting, which significantly increases the risk for bone injuries and fractures.
Patients with end-stage bone cancer also commonly develop lung and breathing problems as a result of cancer growth. The National Cancer Institute indicates that bone cancer very commonly metastasizes to lung tissue and forms harmful colonies of cancer growth within the lungs. As the bone cancer grows in the lung, the increasing tumor size progressively decreases lung capacity, leading to shortness of breath, difficulty breathing and lightheadedness. Bone cancer cells growing in the lungs also actively damage the surrounding lung tissue to provide more room for cancer growth. This damage to the lung tissue can cause bone cancer patients to cough up bloody sputum or experience chest pain. Clusters of cancer growth in the lungs may require surgery or radiation treatment to slow their growth.
Late-stage bone cancer patients often experience a significant amount of pain associated with their cancer growth, reports Medline Plus. In addition to the pain associated with bone fractures and lung damage that can occur from bone cancer growth, patients often experience pain caused by abnormal bony growths. Bone cancers classified as osteoblastic result from the overproliferation of osteoblasts, the bone-depositing cells. When these cells become cancerous, the affected bone is characterized by an increase in the rate of new bone deposition. As a result, patients with osteoblastic bone cancers can develop extensive bony outgrowths that can place pressure on surrounding nerves and muscle tissue, leading to bone pain. The growths can also disrupt normal joint movement and cause excess friction, leading to joint pain. Patients with bone cancer can control their pain with analgesic medications.