Kidney cancer is a disease in which cancer cells grow in the
kidneys. The kidneys are two bean-shaped organs, located just
above the waist, on each side of the spine. Their main function
is to filter the blood and produce urine by which the body rids
itself of waste products and excess water. Cancer occurs when
cells in the body (in this case kidney cells) 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
tissue and spread to other parts of the body. A benign tumor
does not invade or spread. There are two main types of kidney
cancer: Wilms tumor, which occurs predominantly in children, and
renal cell carcinoma in adults. The cells that line the ureter
may also give rise to transitional cell cancer, and the
connective tissues of the kidney may produce sarcomas, which are
rare. A risk factor is some