Kidney cancer, also called renal cancer, refers to a malignancy
that originates 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. The body can
function with only one kidney. 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 types of renal cell
cancer are differentiated by cell type. They include clear cell,
papillary, chromophobe, collecting duct, and unclassified. The
other types of cancer that can develop in the kidneys are
transitional cell carcinoma, whic