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Cancer of the Ureter and Renal Pelvis

Under normal circumstances, the kidneys work like clockwork, cleaning the blood and removing wastes from the body. The cells lining the urinary tract are called urothelial cells. But what happens when the urothelial cells lining of the urinary tract multiply uncontrollably and form tumors? Although blood in your urine or pain in your side may signal a benign problem, it could mean a malignancy or a urothelial cancer. The information below should help you understand cancer of the ureter and renal pelvis.

What happens under normal conditions?

The kidneys are the body's sophisticated filtering system. These two bean-shaped organs, located near the middle of the back below the rib cage, filter about 200 quarts of blood daily to sift out about two quarts of extra water and waste products as urine. The actual processing occurs in millions of tiny units, called nephrons, which contain equally tiny blood vessels, glomeruli and urine-collecting tubules. Together, they host a complicated chemical exchange in which nutrients are recaptured for the body while waste products and water are filtered from the blood. The resulting urine is then transported into the kidney's collecting system - the renal pelvis - before moving through the ureters to the bladder, where it is stored until being pushed out the urethra.

What is upper urinary tract cancer?

It is a disease in which cancer cells are found in the tissues lining the collection reservoir (urothelial cells) of the kidneys - the renal pelvis - and/or in the ureters that connect the kidneys to the bladder.

In particular, tumors of the renal calyces, (the outer extensions of the renal pelvis into the parts of the kidneys that do the actual filtering of blood) renal pelvis and ureters originate in the urothelium (also called transitional epithelium), the innermost tissue layer that lines the inner aspect of the bladder, as well as the upper urinary tract. This lining is unique in that it expands and contracts while still providing a barrier to prevent waste products in urine from reentering the bloodstream. But as such, the urothelium is also a target for cancer because the cells are exposed constantly to chemicals and other carcinogens filtered out of the bloodstream and into the urinary tract during the filtering process of the kidney. These carcinogens are capable of stimulating uncontrollable cell division or growth.

Thus, it is not surprising that urothelial cancer is the fifth most common non-skin malignancy in the United States, often occurring after many decades of exposure to a variety of carcinogenic products (e.g., chemicals, radiation or tobacco). It is also not surprising that because the renal calyces, renal pelvis, ureters and bladder share common urothelial cells, the cancers involving these organs often appear and behave similarly. The difference, however, is that because the bladder acts as a reservoir, it may be at greater cancer risk since its urothelial cells are exposed for prolonged periods to potentially harmful substances. Under certain conditions, such as when the urine has an unusually high concentration of carcinogens, cancer may also occur in the kidney or ureters.

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Information provided by the American Urological Association.