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, sometimes referred to as hypernephroma, occurs in the cells lining the kidneys (epithelial cells). It is the most common type of kidney cancer. Eighty-five percent of all kidney tumors are renal cell carcinomas. Wilms' tumor is a rapidly developing cancer of the kidney most often found in children under four years of age.
Description
The kidneys are a pair of organs shaped like kidney beans that lie on either side 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 called the ureter into the bladder. Urine is held in the bladder until it is discharged from the body. Renal cell carcinoma (RCC) generally develops in the lining of the tubules that filter and clean the blood. Cancer that develops in the central portion of the kidney (where the urine is collected and drained into the ureters) is known as transitional cell carcinoma of the renal pelvis. Transitional cell cancer is similar to bladder cancer. Wilms' tumor is the most common type of childhood kidney cancer and is distinct from kidney cancer in adults.
Demographics
Kidney cancer accounts for approximately 3% of all cancers. In the United States, kidney cancer is the tenth most common cancer and the incidence has increased by 43% since 1973; the death rate has increased by 16%. There are approximately 20, 000 new cases of kidney cancer found each year. There are approximately 95, 000 deaths per year worldwide due to kidney cancer. RCC accounts for 90-95% of malignant neoplasms that originate from the kidney.
Kidney cancer occurs most often in men over the age of 40. The median age of diagnosis is 65. Men are twice as likely as women are to have cancer of the kidney.
Causes and symptoms
The causes of kidney cancer are unknown, but there are many risk factors associated with kidney cancer. The risk factors listed from greatest to smallest include:
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.
Diagnosis
A diagnostic examination for kidney cancer includes taking a thorough medical history and making a complete physical examination in which the doctor will probe (pal-pate) 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 red blood 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 urography (also called pyelogram or IVP) may be ordered. An IVP is an x-ray test in which a dye is injected into a vein in the arm. The dye travels through the body, and when it is concentrated in the urine to be discharged, 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. Ultrasound is a painless and non-invasive procedure that can be used to detect even very small kidney tumors. Imaging tests such as computed tomography (CT) scans and magnetic resonance imaging (MRI) can be used to evaluate the kidneys and the surrounding organs. These tests are used to check whether the tumor has spread outside the kidney to other organs in the abdomen. If the patient complains of bone pain, a special x ray called a bone scan may be ordered to rule out spread to the bones. A chest x ray may be taken to rule out spread to the lungs.
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 examined under 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).
Staging, treatment, and prognosis
Staging
Staging guidelines for kidney cancer are as follows (2.5 cm equals approximately 1 in):
Stage I: Primary tumor is 5 cm or less in greatest dimension and is limited to the kidney, with no lymph node involvement.
Stage II: Primary tumor is larger than 5 cm in greatest dimension and is limited to the kidney, with no lymph node involvement.
Stage III: Primary tumor may extend into major veins or invade adrenal glands or perinephric tissues, but not beyond Gerota's fascia. There may be metastasis in a single lymph node.
Stage IV: Primary tumor invades beyond Gerota's fascia. Metastasis in more than one lymph node. Possible metastasis to distant structures in the body.
Treatment
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 the patient's age, general health, and medical history.
The primary treatment for kidney cancer that has not spread to other parts of the body, which is a Stage I, II, or III tumor, is surgical removal of the diseased kidney (nephrectomy). Because most cancers affect only one kidney, the patient can function well on the one remaining. Two types of surgical procedure are used. Radical nephrectomy removes the entire kidney and the surrounding tissue. Sometimes, the lymph nodes surrounding the kidney are also removed. Partial nephrectomy removes only part of the kidney along with the tumor. This procedure is used either when the tumor is very small or when it is not practical to remove the entire kidney. It is not practical to remove a kidney when the patient has only one kidney or when both kidneys have tumors. There is a small (5%) chance of missing some of the cancer. Nephrectomy can also be useful for Stage IV cancers, but alternative surgical procedures such as transarterial angioinfarction may be used.
Radiation therapy, which consists of exposing the cancer cells to high-energy gamma rays from an external source, generally destroys cancer cells with minimal damage to the normal tissue. Side effects are nausea, fatigue, 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 much use in destroying the kidney cancer cells. Therefore radiation therapy is not used very often as a treatment for cancer or as a routine adjuvant to nephrectomy. Radiotherapy, however, is used to manage metastatic kidney cancer.
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.
Immunotherapy or immunologic therapy, a form of treatment in which the body's immune system is harnessed to help fight the cancer, is a new mode of therapy that is being tested for kidney cancer. Clinical trials with substances produced by the immune cells (aldesleukin and interferon) have shown some promise in destroying kidney cancer cells. These substances have been approved for use but they can be very toxic and produce severe side effects. The benefits derived from the treatment have to be weighed very carefully against the side effects in each case. Immunotherapy is the most promising systemic therapy for metastatic kidney cancer.
Prognosis
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.
Alternative and complementary therapies
There are several healing philosophies, approaches, and therapies that may be used as supplemental or instead of traditional treatments. All of the items listed may have varying effectiveness in boosting the immune system and/or treating a tumor. The efficacy of each treatment also varies from person to person. None of the treatments, however, have demonstrated safety or effectiveness on a consistent basis. Patients should research such treatments for any potential dangers (laetrile, for example, has caused death due to cyanide poisoning) and notify their physician before taking them.
Side effects of treatment, as well as nutrition, emotional well-being, and other complications, are all parts of coping with cancer. There are many possible side effects for a cancer treatment that include:
Anxiety, depression, loss, post-traumatic stress disorder, sexuality, and substance abuse are all possible emotional side-effects. Nutrition and eating before, during, and after a treatment can also be of concern. Other complications of coping with cancer include fever and pain.
Clinical trials
There are many clinical trials in place studying new types of radiation therapy and chemotherapy, new drugs and drug combinations, biological therapies, ways of combining various types of treatment for kidney cancer, side effect reduction, and improving quality of life. Immunostimulatory agents and gene-therapy techniques that modify tumor cells, antiangiogenesis compounds, cyclin-dependent kinase inhibitors, and differentiating agents are all being investigated as possible therapies. Consult <http://ClinicalTrials.gov> and your doctor for a list of kidney cancer clinical trials.
Prevention
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 and tobacco has been shown, avoiding tobacco is the best way to lower one's risk of 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.
Berkow, Robert, ed. The Merck Manual of Diagnosis and Therapy, 16th ed. Rahway, NJ: Merck Research Laboratories, 1997.
Dollinger, Malin, Ernest H. Rosenbaum, and Greg Cable. Everyone's Guide to Cancer Therapy. How Cancer Is Diagnosed, Treated, and Managed Day to Day. Kansas City: Andrews McMeel, 1998.
Murphy, Gerald P., Lois B. Morris, and Dianne Lange. Informed Decisions: The Complete Book of Cancer Diagnosis, Treatment and Recovery. New York: Viking, 1997.
Scher, H.I., and R.J. Motzer. "Renal Cell Carcinoma." In Harrison's Principles of Internal Medicine. Fauci, Anthony, et al, eds. New York: McGraw-Hill, 1998.
PERIODICALS
Dutcher, J.P. "Immunotherapy: Are We Making a Difference?"Current Opinion in Urology (September 2000): 435-9.
Godley, P.A., and K.I. Ataga. "Renal Cell Carcinoma." Current Opinion in Oncology (May 2000): 260-4.
Vogelzang, N.J., and W.M. Stadler. "Kidney Cancer." Lancet(November 1998): 1691-6.
ORGANIZATIONS
American Cancer Society (National Headquarters). 1599Clifton Rd. NE, Atlanta, GA 30329. (800) 227-2345. <http://www.cancer.org.>
American Foundation for Urologic Disease. E-mail: admin@afud.org. Cancer Research Institute (National Headquarters). 681 Fifth Ave., New York, NY 10022. (800) 992-2623. <http://www.cancerresearch.org>.
—The surgical removal and microscopic examination of living tissue for diagnostic purposes.
Bone scan
—An x-ray study in which patients are given an intravenous injection of a small amount of a radioactive material that travels in the blood. When it reaches the bones, it can be detected by x ray to make a picture of their internal structure.
—A medical procedure in which a series of x-ray images are made and put together by a computer to form detailed pictures of areas inside the body.
Hematuria
—Blood in the urine.
Immunotherapy
—Treatment of cancer by stimulating the body's immune defense system.
Intravenous pyelogram (IVP)
—A procedure in which a dye is injected into a vein in the arm. The dye travels through the body and concentrates in the urine to be discharged. It outlines the kidneys, ureters, and the urinary bladder. An x-ray image is then made and any abnormalities of the urinary tract are revealed.
Magnetic resonance imaging (MRI)
—A medical procedure used for diagnostic purposes in which pictures of areas inside the body can be created using a magnet linked to a computer.
Nephrectomy
—A medical procedure in which the kidney is surgically removed.
Primary tumor
—A cancer's origin or initial growth.
Radiation therapy
—Treatment with high-energy radiation from x-ray machines, cobalt, radium, or other sources.
Renal ultrasound
—A painless and non-invasive procedure in which sound waves are bounced off the kidneys. These sound waves produce a pattern of echoes that are then used by the computer to create pictures of areas inside the kidney (sonograms).
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