Kidney cancer, also called renal cancer, refers to a cancer that begins in the kidneys. The kidneys are organs that filter the blood to remove liquid waste products and produce urine. Humans have two kidneys, a left and a right.
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Kidney cancer occurs when cells in the kidney divide without control or order. Normally, cells divide in a regulated manner. If cells keep dividing uncontrollably when new cells are not needed, a mass of tissue forms, called a growth or tumor. The term cancer refers to malignant tumors, which can invade nearby tissues and can spread to other parts of the body. A benign tumor does not invade or spread.
Different types of cancer can develop in the kidneys. The most common is renal cell carcinoma. The other types of cancer that can develop in the kidneys are transitional cell carcinoma, Wilms’ tumors, and renal sarcomas.
Who Is Affected
More men than women develop kidney cancer. Most cases occur in people aged 50 to 70, but it can develop in children and adults of any age.
Causes and Complications
Renal cancers typically develop due to genetic changes called mutations. These mutations may be inherited, but most occur after birth. Exposure to cancer-causing substances, such as tobacco products, can trigger a genetic mutation. The chemicals in tobacco smoke are absorbed into the bloodstream. When the kidneys filter the blood, these substances can build up in the kidney, damage the cells, and lead to cancer. While exposure to cancer-causing substances is a risk factor for renal cell carcinoma, in most cases the cause is unknown.
Kidney cancers sometimes grow to a very large size before they are detected. Symptoms from growth of the tumor in the kidney and surrounding areas include pain in the abdomen or back, blood in the urine, fever, and weight loss. Symptoms associated with the spread of kidney cancer depend on where the cancer is located. The condition may spread to almost all parts of the body, including the lungs, bones, liver, adrenal gland, and the other kidney. Pain is common in later stages of this disease. Kidney cancer may interfere with the body's ability to filter the blood, which may require
treatments in some cases.