Renal cell cancer or renal cell carcinoma is a malignant cancer of the kidneys. It is also referred to as hypernephroma by medical professionals. Cancer cells develop in the lining of the kidney tubules to form a tumor. Renal cell carcinoma is the most common kidney cancer in adults, accounting for over 90 percent of all diagnosed kidney cancer cases. The incidence of renal cell carcinoma development has increased over the years today, three people in every 10,000 are affected. This figure translated to 38,800 new cases and a mortality rate of 12,800 in 2006 according to the American Cancer Society. Renal cell carcinoma is twice as common for males as it is for females, with the average initial diagnosis set at age 55. The highest incidence of all kidney cancer is found in the United States, Canada, Northern Europe, Australia and New Zealand. Nations with the lowest incidence rates are Thailand, China and the Philippines.
The kidneys are fist-sized, bean-shaped organs that weigh four to five ounces each. Most individuals have two kidneys, but humans are able to survive with the use of less than one complete kidney. The kidneys are fixed to the upper back wall of the abdominal cavity and are protected by the lower ribcage. Each kidney is composed of one million glomeruli (microscopic filtering pockets). These glomeruli each connect to a separate tubule. The combination of a glomerulus and a tubule is known as a nephron. The nephron is the basic structural and functional unit of the kidney. It regulates water and soluble substances by filtering blood, reabsorbing needed materials and excreting waste as urine. The urine then passes from the kidney into the bladder through a tube known as the ureter. This liquid waste is stored in the bladder until it is time to excrete it from the body.
The kidneys produce two hormones erythropoietin (EPO) and calcitriol and one enzyme rennin that are essential for normal body functioning. EPO acts on bone marrow to trigger the production of red blood cells. The production of EPO is stimulated by bleeding or moving to high altitudes where oxygen is scarcer. Calcitriol is the active form of vitamin D. It acts on intestinal cells to promote calcium absorption from food and helps to move calcium from bones into the blood stream. Calcitriol is extremely important for the development of strong and healthy bones. Renin is essential for adjustments in blood volume and blood pressure. It interacts with a number of substances, including aldosterone a hormone produced by the adrenal glands to help regulate blood pressure as well as sodium and potassium levels in the blood. Renin also stimulates thirst sensors in the brain, which ensures that bodily fluid levels are normal.
The tumor associated with renal cell cancer is a solid, hypervascular (contains an excessive number of blood vessels) lesion that disturbs the shape of the kidney. One lesion is normal, but several tumors have been known to grown in one or both of the kidneys. The cancer cells form cords, papillae, tubules or nests, and are polygonal and enlarged. It is generally of an irregular shape, growing larger in the front. The tumor is often yellow in color due to the accumulation of lipids. Ten percent of renal cell carcinoma tumors have calcifications and some may have macroscopic fat.