Kidney Cancer
The kidney is an organ in the urinary system and is involved in filtering the blood. It removes toxins and waste products from the blood and turns them into urine, which is then excreted. Sometimes the cells of the kidney can become cancerous, which means that they begin to grow abnormally fast. Although it is not entirely known how this happens, scientists have determined a number of risk factors that increase the risk of kidney disease. These include some preventable risk factors, such as smoking, low intake of vitamin E, and a high calorie diet, as well as some non-preventable factors, such as a family history of kidney cancer and polycystic kidney disease.
Metastasis
Kidney cancer often does not cause any symptoms until it has turned into "advanced" kidney cancer. When kidney cancer becomes advanced, it means that it has metastasized. Metastasis occurs when the cancer cells develop the ability to break free of the original tumor and penetrate through healthy tissue, which allows the cancer to spread. For this to happen, the cancer cells need to secrete special proteins that allow them to break down the barriers and membranes that separate different kinds of tissue. Kidney cancer most commonly spreads to the lungs, the brain and the bones.
Bone Metastasis
Kidney cancer is able to cause joint pain when it metastasizes to the bones. When the kidney cancer spreads to the bones, it can cause weakening of the bones as normal bone tissue is replaced with cancerous cells. Because the cancerous cells are not as strong as the normal bone cells, this makes it easier for the bone to break. Sometimes this causes small fractures to appear around the joints, leading to joint pain. Other times this causes bone deformities that can cause changes in posture and muscle use, which can also cause joint pain.
