Kidney cancer can affect both men and women, although it is more common in men. For men, kidney cancer will be the seventh most commonly diagnosed cancer in 2007, accounting for an estimated 4 percent of all cancers in men. An estimated 51,190 new cases of kidney cancer will be diagnosed in 2007, according to the American Cancer Society. The condition is most common in people between 50 and 70 years old.
The kidneys are two bean-shaped organs about the size of a fist. They are located toward the back, about midway down the back, on each side. The kidneys filter waste to create urine and release hormones important to the body. Kidney cancer occurs as cells within the kidney grow and divide uncontrollably and develop the ability to spread elsewhere in the body.
Another name for kidney cancer is renal cancer. "Renal" is the Latin word for kidney. Cancer of the kidney may also be called renal cell carcinoma. The most common type of kidney cancer is renal cell carcinoma (renal adenocarcinoma). The other two main types of kidney cancer are transitional cell carcinoma and Wilm's tumor (which mostly affects children).
The exact causes of kidney cancer are not known. Risk factors for developing kidney cancer include smoking, among others. Smoking doubles the risk of kidney cancer. A high-fat diet and being obese (very overweight) are also risk factors for kidney cancer. A family history of kidney cancer increases the risk that an individual will develop the condition.