Kidney cancer is a disease in which the cells in certain tissues of the kidney start to grow uncontrollably and form tumors. Renal cell carcinoma, which occurs in the cells lining the kidneys (epithelial cells), is the most commontype of kidney cancer. Eighty-five percent of all kidney tumors are renal cell carcinomas.
The kidneys are a pair of organs shaped like kidney beans that lie on eitherside of the spine just above the waist. Inside each kidney are tiny tubes (tubules) that filter and clean the blood, taking out the waste products and making urine. The urine that is made by the kidney passes through a tube calledthe ureter into the bladder. Urine is held in the bladder until it is discharged from the body. Renal cell carcinoma generally develops in the lining of the tubules that filter and clean the blood.
The causes of kidney cancer are unknown, but men seem to have twice the riskof contracting the disease. There is a strong association between cigarette smoking and kidney cancer. Working around coke ovens has been shown to increase people's risk of developing this cancer. Certain types of painkillers thatcontain the chemical phenacetin are associated with kidney cancer. Obesity may be yet another risk factor for kidney cancer.
The most common symptom of kidney cancer is blood in the urine (hematuria). Other symptoms include painful urination, pain in the lower back or on the sides, abdominal pain, a lump or hard mass that can be felt in the kidney area,unexplained weight loss, fever, weakness, fatigue, and high blood pressure.
A diagnostic examination for kidney cancer includes taking a thorough medicalhistory and making a complete physical examination in which the doctor willprobe (palpate) the abdomen for lumps. Blood tests will be ordered to check for changes in blood chemistry caused by substances released by the tumor. Laboratory tests may show abnormal levels of iron in the blood. Either a low redblood cell count (anemia) or a high red blood cell count (erythrocytosis) may accompany kidney cancer. Occasionally, patients will have high calcium levels.
If the doctor suspects kidney cancer, an intravenous pyelogram (IVP) may be ordered. An IVP is an x-ray test in which a dye in injected into a vein in thearm. The dye travels through the body, and it outlines the kidneys, ureters,and the urinary bladder. On an x-ray image, the dye will reveal any abnormalities of the urinary tract. The IVP may miss small kidney cancers.
Renal ultrasound is a diagnostic test in which sound waves are used to form an image of the kidneys. Imaging tests such as computed tomography scans (CT scans) and magnetic resonance imaging (MRI) can be used to check whether the tumor has spread outside the kidney to other organs in the abdomen. A kidney biopsy is used to positively confirm the diagnosis of kidney cancer. During this procedure, a small piece of tissue is removed from the tumor and examinedunder a microscope. The biopsy will give information about the type of tumor,the cells that are involved, and the aggressiveness of the tumor (tumor stage).
Each person's treatment is different and depends on several factors. The location, size, and extent of the tumor have to be considered in addition to thepatient's age, general health, and medical history. The primary treatment forkidney cancer that has not spread to other parts of the body is surgical removal of the diseased kidney (nephrectomy). Because most cancers affect only one kidney, the patient can function well on the one remaining. Radiation therapy, which consists of exposing the cancer cells to high-energy gammarays from an external source, generally destroys cancer cells with minimal damage to the normal tissue. Side effects are nausea, tiredness, and stomach upsets. These symptoms disappear when the treatment is over. In kidney cancer, radiation therapy has been shown to alleviate pain and bleeding, especially when the cancer is inoperable. However, it has not proven to be of muchuse in destroying the kidney cancer cells. Therefore radiation therapy is not used very often.
Treatment of kidney cancer with anti cancer drugs (chemotherapy) has not produced good results. However, new drugs and new combinations of drugs continue to be tested in clinical trials.
Because kidney cancer is often caught early and sometimes progresses slowly,the chances of a surgical cure are good. It is also one of the few cancers for which there are well-documented cases of spontaneous remission without therapy.
The exact cause of kidney cancer is not known, so it is not possible to prevent all cases. However, because a strong association between kidney cancer andtobacco has been shown, avoiding tobacco is the best way to lower one's riskof developing this cancer. Using care when working with cancer-causing agents such as asbestos and cadmium and eating a well-balanced diet may also help prevent kidney cancer.