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Overview of this condition

While cancer in its various forms can strike virtually any organ of the body, only rarely does it seem to attack the kidneys. This is fortunate, because in addition to being among its more delicate organs, the kidneys perform some of the body's most vital functions.

In the United States, renal adenocarcinoma -- cancer of the kidney -- accounts for about 3% of all adult cancers. About 30,000 new cases are diagnosed annually. The disease occurs almost twice as often in men than in women and generally appears between the ages of 50 and 70, although it can appear earlier.

It is important to realize that while kidney cancer is a serious illness, with timely diagnosis and treatment it can be cured. If found early enough, the five-year survival rate for patients with kidney cancer ranges from 79% to 100%, depending upon how early it is diagnosed. More than 100,000 survivors of kidney cancer are alive in the United States today.

The Kidneys
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 a 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: erythropoitein (EPO), which triggers the production of red blood cells in bones; renin, which regulates blood pressure; and vitamin D, which helps regulate the body's calcium balance, necessary for healthy bones.

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% 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.

Discovery and Prognosis

What are the signs and symptoms of the condition?

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.

While these primary symptoms can indicate the presence of RCC, in most cases they are the result of other illnesses. Nevertheless, people who have any of these symptoms should see their urologist or family doctor as soon as possible.

What are the risks and causes of this condition?

No one can say conclusively what causes RCC. Nevertheless, research has revealed a variety of risk factors that appear to be associated with the disease.

• Smoking
  There is strong evidence that cigarette, pipe and cigar smoking doubles a person's risk of developing RCC. Researchers estimate that from 25% to 30% of all renal cell cancers are directly attributable to smoking.

Genetic Factors

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 that forms 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: von Hippel-Lindau syndrome, a disease that causes multiple tumors of the brain, spine, eyes, adrenal glands, pancreas, inner ear, testicles and kidneys; and 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 and pancreas and, in some cases, RCC.

Other Risk Factors

• Diet/Weight -- a high-fat diet and obesity are thought to present an increased risk of RCC.
• Extended Dialysis -- 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.
• Estrogen -- Though there is no conclusive proof that estrogens cause RCC in humans, tests have shown that animals can develop the disease when given estrogens.
• Gender -- Men are twice as likely to develop RCC than women.

Diagnostic Tests

If the physician suspects the patient's symptoms are caused by RCC, he or she likely will prescribe a series of examinations, procedures and laboratory tests to confirm the diagnosis.

Physical Exam 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.

Imaging
The preliminary workup usually is followed by one or more imaging procedures to obtain a visual picture of the kidney(s) and any abnormalities that may be causing the patient's symptoms. A variety of modern, accurate, imaging procedures is available to assist the physician in this process. Most of these procedures are essentially painless, although a few require the injection of a special "tracer" material (dye or low-level radioactive isotope) into the patient's bloodstream.

Computed Tomographic (CT) Scan
A computer-assisted tomography scan -- also known as CT or CAT scan -- is a type of cross-sectional X-ray that produces a series of three-dimensional images of internal organs and glands. It can detect tumors and, in some cases, lymph nodes enlarged by cancer, although some authorities suggest its results in the latter case are insufficiently clear to generate conclusive results.

Magnetic Resonance Imaging (MRI)
Similar in some respects to a CAT scan, an MRI uses large magnets to project magnetic waves through the body and create computer-generated cross-sectional images of internal organs.

Ultrasound
Ultrasound testing techniques use sound waves projected into the body to produce a viewable image of internal organs, structures and, in some cases, tumors. In this painless procedure, a jelly-like lotion is applied to the patient's pelvic and kidney areas, and a small device that emits ultrasonic pulses is slowly passed over the area. The sonic image thus produced is viewed on a monitor.

Intravenous Pyelogram (IVP)
The doctor also may prescribe a procedure called an intravenous pyelogram (IVP), which involves injecting a special dye containing iodine through a vein in the arm into the bloodstream. The dye eventually collects in the urinary system, where it helps improve the contrast for X-rays and gives the doctor a better image of the kidneys, ureters and bladder. By showing up as white on the dark X-ray film, the IVP can disclose a tumor or the damage a tumor may have caused the kidney.

In some cases the physician may request an arteriogram or venacavagram - special X-rays of the blood vessels that supply the kidneys - to check for the presence of tumors in the connecting arteries and veins.

Chest X-ray
If there is reason to believe RCC is present and sufficiently advanced to have metastasized, the doctor may order a standard chest X-ray to determine if it has spread to the lungs or bones in the chest area.

Bone Scan
This is another nuclear imaging procedure used to detect the spread of cancer to bones. It usually is prescribed in cases where aggressive tumors and metastasis are suspected. In a bone scan, a small amount of low-level radioactive material is injected into the body. This material discloses metastatic cancer, as well as some noncancerous diseases, in bones.

Laboratory Tests
In addition to imaging, the physician probably will prescribe one or more laboratory tests to confirm the presence of RCC.

Urinalysis
More than half of all patients with RCC have blood in their urine -- a condition known as hematuria. Often this blood is present in such small amounts or so diffused in the urine that it cannot be seen with the naked eye. To detect hematuria, a microscopic and/or chemical test of the patient's urine usually is prescribed. On occasion, a microscopic procedure called urine cytology may actually disclose cancer cells in the urine.

Blood Tests
Another laboratory procedure typically used in the diagnosis of RCC involves microscopic and/or chemical examination of the patient's blood to detect conditions that indicate the presence of cancer. These tests screen for:

• Anemia - too few red blood cells, a condition caused by internal bleeding, a common cancer symptom;
• Polycythemia - too many red blood cells, sometimes caused by cancerous tumors in the kidney triggering the release of a hormone that increases red blood cell production in the bone marrow, and
• Elevated liver enzymes and hypercalcemia (high blood calcium levels) - both conditions are characteristic of RCC, although precisely why they occur is unknown.

Cystoscopy
Because blood in the urine can result from health problems other than kidney cancer - kidney stones or traumatic kidney injury, for example - the doctor may order a procedure called cystoscopy to determine precisely where the internal bleeding is occurring. In cystoscopy, a long, thin, optical scope, either rigid of flexible, is inserted through the urethra and into the bladder. Through it the operator can make a visual examination of the urethra, bladder or kidneys to locate the site of bleeding.

Fine Needle Aspiration
As noted, the tumors that characterize RCC are made up of malignant (cancerous) cells that grow together in a mass. If imaging or other procedures detect the presence of a tumor, a cell sample may be taken for microscopic examination.

In general, physicians avoid performing needle biopsies of suspected kidney tumors because of the risk of causing bleeding or other complications. However, in some cases the tumor may contain a fluid-filled cyst. By puncturing the cyst with a fine needle, a small amount of this fluid can be drawn out for examination by a pathologist, who will look for cancer cells. This can help determine the type of cancer a patient has, and aid the physician in recommending an appropriate form of treatment. While no longer common, a similar technique can be employed to collect a sample of solid tissue from a noncystic tumor.

Pathology
Broadly speaking, the individual cells that make up RCC tumors fall into four categories, defined by their appearance under microscopic examination: clear cell, granular cell, mixed clear and granular, and sacromatoid or spindle-type. Most studies suggest that the type of cancer cell present indicates the relative aggressiveness of the disease.

Under a microscope, clear cell cancers are the least "abnormal-looking" -- they are rounded or polygonal-shaped and contain an abundance of fat and sugar. The tumors they produce are yellow-to-orange in color. Clear cell cancers are thought to be the least aggressive (likely to spread) and respond more favorably to treatment.

Few tumors contain only clear cells, however. Darker granular cells usually are present to a varying degree. These have a larger, darker, nucleus and are full of tiny pink granules called mitochondria. The tumors they produce tend to be gray to white in color. Mitochondria are small, oval bodies that provide energy for cell growth. Their presence indicates a more aggressive form of cancer.

Tumors that contain both clear and granular cells are considered mixed. This is the most common form of RCC and indicates the most aggressive form of kidney cancer.

Mixed tumors that contain spindle-shaped, sacromatoid cells generally are regarded as having the least favorable prognosis. Although tumors composed exclusively of spindle cells are uncommon, the relative presence of sacromatoid cells indicates a form of cancer that tends to grow and spread more quickly.

Grading and Staging of this disease

Grading

Doctors often will assess an RCC by its grade. The grade of a cancer cell is a assessment of its appearance relative to that of a normal, healthy kidney cell. Grading is done on a scale of 1 to 4, with Grade 1 RCCs having cells that differ little from normal. Such cells typically spread slowly and have a good prognosis for treatment. At the opposite end of the scale, a Grade 4 RCC looks extremely different from a normal kidney cell and indicate an aggressive cancer with poor prognosis

Staging this disease

Although grading and the identification of cancer cell types can be helpful in determining a patient's prognosis, most doctors believe that establishing the cancer's stage gives a better indication of a patient's survivability.

Staging allows a physician to gauge the size and location of tumors by using information gathered from such imaging studies as CT scans and MRIs, and information from pathology tests and physical examinations. Once a stage has been established, the physician can attempt to determine how a patient may do over time and decide what type of treatment offers the best potential for success.

Some of the staging factors for RCC that have been shown to influence a patient's prognosis are: whether the cancer has spread to the tissues surrounding the kidney; if it extends to contiguous organs; whether nearby lymph nodes (the small, bean-shaped structures found throughout the body that produce and store infection-fighting cells) are involved; and how far the cancer has spread.

There are two basic staging systems for RCC:

The Robson System, devised in 1969, is a modification of an earlier system devised by Flocks and Kadesky in 1958. It divides patients into stages labeled 1 to 4.

The TMN (Tumor-Node-Metastases) System, adopted by the American Joint Committee on Cancer and the International Union Against Cancer, uses stages generally similar to those of the Robson System. This second staging system, also called the international classification system, is becoming more widely accepted because it provides a more accurate description of the tumor involvement.

Like the Robson System, the TMN System also stages RCC tumors at four intervals:

In addition to stages, however, the TMN System also uses expanded alphanumeric subcategories to better reflect specific areas and degrees of infection. These are as follows:

Primary tumor (T); all sizes measured in greatest dimension:

Regional Lymph Nodes (N):

Distant Metastasis (M):

• Surgery -- The removal of cancerous tissue in an operation.
• Chemotherapy -- Using drugs or chemicals to kill cancer cells.
• Radiation Therapy -- The use of high-energy radiation to kill cancer cells.
• Hormone Therapy -- Use of hormones to prevent cancer cell growth.
• Biological or Immunotherapy -- The use of compounds produced by the body's own disease-fighting system -- or laboratory-produced copies of them -- to kill cancer cells.

In some cases, two or more forms of treatment may be used jointly, such as surgery to remove a primary tumor, followed by radiation treatment or chemotherapy to kill any cancer cells that may have been left behind.

A sixth form of treatment, gene therapy, is now being studied by researchers who think inherited genetic mutations may be a prime factor in many cases of RCC. Gene therapy seeks to understand why these genetic changes happen, turning normal, healthy kidney cells into cancerous tumors. If researchers can unlock these secrets, they eventually may be able to develop a process that uses normal genes to overcome or reverse the cancer-causing process. Currently, however, gene therapy is more a potential than practical treatment option.

Surgery
Some form of surgery usually is required to combat RCC. Without it, in most cases the patient's chances of survival are poor. There are several surgical options open to the patient and physician; which one is most appropriate will depend on an assessment of the patient's condition and the cancer's stage.

• Radical Nephrectomy
  The most common form of surgery for RCC, radical nephrectomy involves removal of the entire kidney, often along with the attached adrenal gland, surrounding fatty tissues and nearby lymph nodes (regional lymphadenectomy), depending upon how far the cancer has spread.
• Partial Nephrectomy
  In some cases it may be possible to remove only the cancerous tissue and part of the kidney, particularly if the tumor is small and confined to the very top or bottom of the kidney. A partial nephrectomy also may be the procedure of choice for patients with RCC in both kidneys or those who have only one functioning kidney.
• Arterial Embolization
  This procedure usually is reserved for patients whose overall health does not permit surgery, such as those with heart or lung problems. In arterial embolization, a very small tube called a catheter is inserted through a blood vessel in the groin and passed up to the kidney. There it is used to inject a small piece of gelatin sponge into the artery that supplies blood to the cancerous kidney. This cuts off the flow of blood to the kidney and the cancerous tumor, which die. The kidney usually is surgically removed at a later date, if and when the patient's overall condition permits.

Surgical Risks
Any form of invasive surgery carries certain inherent risks. While not all patients experience complications, patients contemplating kidney surgery should be advised of the possibility of: hemorrhage (bleeding) during surgery (intraoperative) or after surgery (postoperative); infection; damage to organs (spleen, pancreas, large or small bowel) or blood vessels (aorta or vena cava); pneumothorax, the introduction of unwanted air into the chest cavity; incisional hernia, a bulging of the internal organs beneath the surgical incision, caused by imperfect healing or damage to the overlying muscles; and failure of the remaining kidney after one or parts of both have been removed.

Postoperative Prognosis
The natural course of renal cell cancer is more unpredictable than that of most tumors. It is the second most common tumor to undergo spontaneous regression following removal of the primary lesion; this occurs about 0.5% of the time.

Another unusual characteristic of RCC is the variability in the growth of the primary tumor. Once distant disease occurs, survival depends on the extent of the spread and the interval between removal of the kidney and the appearance of the metastases.

Other types of kidney cancer

Transitional Cell Carcinoma
About 6% to 7% of kidney cancers begin not in the kidney itself, but in the renal pelvis, the point where the kidney joins the ureter (the tube running from the kidney to the bladder). These tumors are called transitional cell carcinomas, and are made up of cancer cells different from those that characterize RCC. Research indicates these tumors are caused by cigarette smoking.

Wilms' Tumor
A relatively rare form of kidney cancer, Wilms' tumor (also known as nephroblastoma) accounts for about 5% to 8% of kidney tumors in children. It occurs in about 7 out of every 1 million children around the world per year, regardless of race, and is thought to be caused by genetic mutation that causes abnormal growth within the tubules of the kidney nephrons. The disease occurs equally in boys and girls. It typically first appears in children between 2 and 5 years of age, but has been known to occur rarely in adolescents as old as 15.

Renal Sarcoma
Another rare form of kidney cancer, renal sarcoma is a disease of the kidney's connective tissues that accounts for less than 1% of all kidney tumors. Its symptoms are similar to those of RCC: hematuria, pain in the back or flank, or a lump or mass in the abdomen. In most cases, it is impossible to differentiate renal sarcoma from RCC externally, so the diagnosis usually is made after examination of a CT scan or MRI procedure.

Preferred Treatment by Stage

Follow-up Care and Recurrent Kidney Cancer
Some patients who undergo surgery to remove a cancerous kidney or kidney tumors experience a recurrence of the disease. For this reason, patients usually undergo a regimen of follow-up examinations after surgery, typically at three-month intervals for the first year. These examinations should include a complete physical examination, a chest X-ray, a complete blood workup and assessments of liver and kidney function.

Benign Tumors of Kidney Cancer

• Renal Adenoma
  The most common form of benign, solid kidney tumor, renal adenomas are typically small, low-grade growths. Their cause is unknown. Because they usually are asymptomatic, their incidence in the live population is unknown, although one study found them present in 7% to 22% of autopsy cadavers. In rare cases, where they have grown large enough to erode the function of the kidney or adjacent vessels, symptoms similar to those of RCC have been known to occur.

  Adenomas look much like low-grade RCCs under a microscope. In fact, while they are considered benign, there is presently no known cellular classification to differentiate them from RCCs. Many researchers and physicians regard them as early-stage precancers, to be treated accordingly.

• Renal Oncocytoma
  Oncocytomas are a type of benign, usually asymptomatic, tumor that can grow quite large. They can develop throughout the body and are not unique to the kidneys. Their cause is unknown, and they appear with greater frequency in men than in women. Typically, they are discovered incidentally by ultrasound, IVP, CT or MRI scan during an examination for some other health problem.

  Under a microscope, many oncocytomas resemble early-stage RCCs. Many physicians regard them as precancerous growths to be surgically removed unless the patient's age or overall health condition dictates otherwise.

• Angiomyolipoma
  Also known as renal hamartoma, angiomyolipomas are rare benign tumors usually caused an inherited genetic mutation. They can occur on an isolated, individual basis, but most often are associated with the rare genetic disease called tuberous sclerosis, an affliction characterized by small tumors of the blood vessels, resulting in numerous bumps on the skin, mental retardation, seizures, cysts in the kidneys, liver and pancreas, and, in some cases, RCC. About 80% of persons diagnosed with tuberous sclerosis also have hamartoma.

  In patients without tuberous sclerosis, hamartoma most often occurs in middle-aged women. Most cases are discovered when the patient undergoes a CT scan for an unrelated abdominal problem, complains of gastrointestinal discomfort, or suffers a sudden hemorrhage caused by the rupture of a large tumor.

  Management of the condition depends on the size of the tumors and the severity of the symptoms they produce. Asymptomatic patients and those with small tumors usually are not treated; instead, they are observed periodically with an eye toward surgery if the tumors grow or produce symptoms. Because of the potential for spontaneous rupture and life-threatening hemorrhage, patients with large tumors usually are considered candidates for some form of surgical treatment, ranging from partial nephrectomy to arterial embolization.

• Fibroma
  Fibromas are tumors of the fibrous tissue on, in or surrounding the kidney. They are rare and most often found in women. Their cause is unknown. Usually they grow on the periphery of the kidney and can become large before becoming clinically obvious. Most are asymptomatic. While generally benign, these tumors have no special characteristics to differentiate them from other, malignant tumors of the kidney. Because of this uncertainty of diagnosis, most physicians treat them surgically. Partial or radical nephrectomy is the standard approach.

• Lipoma
  Among the rarest of renal tumors, lipomas appear to originate in the fat cells within the renal capsule or surrounding tissue. They typically occur in middle-aged women, can grow very large and produce pain and hematuria. Like many benign tumors, they are suspected of harboring potential for turning cancerous, and usually are treated with surgical excision, typically involving total nephrectomy.

For More Information

National Institutue of Diabetes and Digestive & Kidney Diseases
http://www.niddk.nih.gov

American Cancer Society
1599 Clifton Road NE
Atlanta, GA 30329-4251
Phone: 1-800-ACS-2345
http://www.cancer.org

National Kidney and Urologic Diseases Information
3 Information Way
Bethesda, MD 20892-3580
Phone: 301-654-4415
http://www.niddk.nih.gov/health/kidney/nkudic.htm

Kidney Cancer Association
1234 Sherman Avenue, Suite 203
Evanston, IL 60202-1375
Phone: 1-800-850-9132
http://www.nkca.org

National Kidney Foundation
30 East 33rd Street
New York, NY 10016
Phone: 1-800-622-9010
http://www.kidney.org

American Association of Kidney Patients
100 South Ashley Drive, Suite 280
Tampa, FL 33606-5348
Phone: 1-800-749-2257
http://www.aakp.org

National Cancer Institute
9000Rickville Poke
Bethesda, MD 20205
Phone: 1-800-4-CANCER
http://www.nci.nih.gov
http://www.cancernet.nci.nih.gov

National Kidney Foundation
30 East 33rd Street
New York, NY 10016
Phone: 1-800-622-9010
http://www.nkca.org

American Association of Kidney Patients
100 South Ashley Drive, Suite 280
Tampa, FL 33606-5348
Phone: 1-800-749-2257
http://www.aakp.org

National Cancer Institute
9000Rickville Poke
Bethesda, MD 20205
Phone: 1-800-4-CANCER
http://www.nci.nih.gov
http://www.cancernet.nci.nih.gov