The kidneys are an essential part of the body’s urinary system. Bean–shaped organs about the size of a fist, the two kidneys are located near the middle of the back, just below the rib cage. Their primary function is to detoxify the bloodstream, filtering out impurities and waste products through tiny filters called nephrons. Each kidney contains about one million nephrons, within which tiny blood vessels called capillaries are intertwined with minute waste–carrying tubes called tubules. Wastes collected by these filters are passed on to the bladder through tubes called ureters, where they are excreted in the form of urine.
The kidneys also produce three important hormones: erythropoietin (EPO), which triggers the production of red blood cells in bones; rennin, which regulates blood pressure; and vitamin D, which helps regulate the body’s calcium balance, necessary for healthy bones.
Renal Cell Carcinoma (RCC)
There are several forms in which cancer may afflict the kidneys. The most common is renal cell carcinoma (RCC), a disease that accounts for approximately 85 per cent of all kidney cancers. RCC is a condition in which malignant (cancerous) cells develop in the lining of the kidney’s tubules. These cells typically grow into a mass, called a tumor. Single tumors are the norm, although more than one tumor can develop simultaneously within one or both kidneys.
Early diagnosis is critically important. As with most cancers, the earlier kidney tumors are discovered, the better a patient’s chances are of being treated successfully. Tumors that have grown large or metastasized (spread) through the bloodstream or lymphatic system to other parts of the body are much more difficult to treat and present a greatly increased risk of mortality.
Risk Factors of Renal Cell Carcinoma
No one can say conclusively what causes Renal Cell Carcinoma. Nevertheless, research has revealed a variety of risk factors that appear to be associated with the disease.
There is strong evidence that cigarette, pipe and cigar smoking doubles a person’s risk of developing Renal Cell Carcinoma. Researchers estimate that about 25 per cent to 30 per cent of all renal cell cancers are directly attributable to smoking.
Overuse of Painkillers
Once popular as over–the–counter painkillers, medications containing phenacetin have been linked to the development of RCC, typically among patients who make an excessive use painkillers.
Studies have shown that an exposure to certain substances increases the risk of RCC. Asbestos, once commonly used as an insulating material, and cadmium, formerly an ingredient in certain colored inks and paints, have been linked to kidney cancer. Persons whose jobs may have brought them in contact with these substances – construction and shipyard workers, painters and printers, for example – may have an increased risk of developing Renal Cell Carcinoma.
While the reason for it remains unclear, people with a family history of kidney cancer appear to be at risk of developing RCC. It is suspected that inherited genetic mutations may be the cause, perhaps triggered by damage to the DNA in the genes. Cigarette smoke for example, is known to contain chemicals that can damage the genes of kidney cells.
Other genetic mutations are thought to be responsible for two of the rarer forms of kidney cancer: The von Hippel–Lindau syndrome – a disease that causes multiple tumors of the brain, spine, eyes, the adrenal glands, pancreas, the inner ear, testicles and kidneys; tuberous sclerosis – a disease characterized by small tumors of the blood vessels, resulting in numerous bumps on the skin, mental retardation, seizures, and cysts in the kidneys, liver, pancreas and in some cases, Renal Cell Carcinoma.
Other Risk Factors
A high–fat diet and obesity are thought to present an increased risk of RCC.
Over time, kidney patients who must be treated with long–term dialysis may develop cysts in their kidneys. While most cysts are not life–threatening, they are considered a risk factor for RCC.
Though there is no conclusive proof that estrogens cause RCC in humans, tests have shown that animals can develop the disease when given estrogens.
Men are twice as likely to develop RCC than women.
Discovery and Prognosis of Renal Cell Carcinoma
Since RCCs can grow to a considerable size before they cause pain or discomfort. Most cases are discovered only after the disease has progressed to a dangerous level. Fortunately, however, many are discovered incidentally – typically when the patient undergoes medical tests for some other ailment. While the discovery usually comes as a shock to the patient, incidental discovery can be a blessing in disguise. This is because tumors discovered at this stage often are not too far advanced in their development and will respond well to treatment. Survival rates in such cases are high. The prognosis is less optimistic when tumors have grown enough to produce symptoms. Often such cancers have metastasized; that is, begun spreading to other organs. Survival rates in such cases are diminished.
Overall, the five–year survival rate for Renal Cell Carcinoma – all stages combined – is about 40 to 45 per cent.
Signs and Symptoms of Renal Cell Carcinoma
The major symptoms of RCC are:
- Blood in the urine (hematuria).
- Pain in the flank (side) or lower back not associated with an injury.
- An abdominal mass or lump in the belly.
- A persistent feeling of fatigue.
- Rapid, unexplained weight loss.
- Fever not caused by a cold or flu, and
- Swelling of the legs and ankles.
If the physician suspects the patient’s symptoms are caused by RCC, he or she is likely to prescribe a series of examinations, procedures and laboratory tests to confirm the diagnosis.
Physical Examination and Medical History
The process usually starts with a thorough physical examination to assess the patient’s overall health and gather as much information as possible about his or her symptoms. A medical history check also will be performed to determine if any known risk factors associated with RCC are present.