About Kidney Cancer
Like most cancers, kidney cancer is named for the part of the body in which it originates. The kidneys are two large, bean-shaped organs located on each side of the spine just above the waist. Their function is to filter the blood and rid the body of liquid waste. As blood flows through the kidneys, tiny tubules filter out excess water, mineral salts and toxins. The kidneys concentrate these waste products into urine, which collects in the middle of each kidney in an area called the renal pelvis (renes is the Latin word for kidneys). Urine exits the kidneys through long, slender tubes called ureters. The ureters are connected to the bladder, where urine is stored until a person urinates.
What are the different types of kidney cancer?
By far the most common type of kidney cancer is renal cell carcinoma, accounting for about 85 percent of cases. There are five main forms of renal cell cancers, each differentiated by the way the cancerous cells appear under a microscope. They include: clear cell (about 70–80 percent of renal cell cancers), papillary (about 10–15 percent of renal cell cancers), chromophobe (about 5 percent), collecting duct (very rare), and “unclassified,” which means the appearance of the cancer cells doesn’t fit into any of the other four main categories (about 5 percent). The type of renal cell carcinoma is important when planning a treatment strategy.
Less common forms of kidney tumors include: transitional cell carcinoma,Wilms’ tumor, renal sarcoma, renal cell adenoma, renal oncocytoma, and angiomyolipoma. Of these types of kidney tumors, transitional cell carcinomas are the most common, accounting for 5–10 percent of cases. This type of cancer begins in the renal pelvis, where the kidney connects to the ureter. The cells look and act in a manner very similar to bladder cancer. [See Bladder Cancer FAQ for more information.]
Wilms’ tumor is the predominant form of kidney cancer found in children. It rarely occurs in adults. About 5–6 percent of all kidney cancers are Wilm’s tumors. Renal sarcomas originate within the connective tissue of the kidney and account for less that one percent of all kidney cancers. The remaining types of kidney tumors – renal adenomas, oncocytomas, and angiomyolipomas – are benign (noncancerous) tumors and are rare.
Note:The remaining information in this Kidney Cancer FAQ pertains only to renal cell carcinomas.Additional information about renal cell carcinomas as well as the less common forms of kidney tumors can be obtained from the National Cancer Institute by calling 1-800-422-6237.
What are the risk factors for kidney cancer?
A risk factor is anything that increases a person’s chance of getting a disease. The leading risk factor for renal cell carcinoma is smoking, with approximately 30 percent of cases in men and 25 percent of cases in women directly attributable to the habit. Research indicates that smokers have double the risk of developing kidney cancer, compared with nonsmokers. This is because some of the carcinogens (cancer-causing substances) from tobacco smoke are absorbed from the lungs and enter the bloodstream. These chemicals are then filtered from the blood by the kidneys, where they can injure kidney cells, potentially causing cancer.
Another risk factor for kidney cancer is workplace exposure to asbestos (an insulating material that is currently banned because of its link with lung cancer and other types of cancer), cadmium (a type of metal used in metalworking), or organic solvents, especially trichloroethylene.
Being overweight also appears to affect risk, with some experts attributing as many as 20 percent of kidney cancer cases to obesity. Obesity appears to influence certain hormones that may play a role in renal cell cancers. Patients who develop cystic disease (cancerous cysts) while on long-term dialysis (a medical procedure that uses a specially designed machine to filter the blood) are at greater risk for renal cell cancer. The cysts are usually found early, however, and can therefore be removed before they spread.
Overuse of painkillers containing the once popular, over-the-counter analgesic phenacetin has also been associated with renal cell carcinoma.
As with all cancers, there are certain risk factors for kidney cancer that are out of our control. Increasing age is one example. Kidney cancer is usually diagnosed in people aged 50–70. Another uncontrollable risk factor is gender: Men are twice as likely as women to develop the disease. This may be because men are more likely to smoke (this trend is changing) and are more likely to be exposed to carcinogenic chemicals at the workplace.
In addition, there are hereditary factors that predispose some people to kidney tumors. Certain genetic mutations (defects), such as von Hippel- Lindau syndrome, significantly raise the risk of developing renal cell carcinoma. Finally, people with a disease known as tuberous sclerosis frequently develop cysts in their kidneys, liver, and pancreas and have an elevated risk of getting renal cell cancer.
Can anything be done to prevent kidney cancer?
Although the causes of renal cell carcinoma are not well understood, there are certain steps a person can take to protect him- or herself against the disease. First, do not smoke. Second, avoid long-term workplace exposure to carcinogenic substances, particularly asbestos, cadmium and organic solvents. If you do work with chemicals, make sure you follow occupational safety practices. Third, maintain a healthy weight.
What are the signs and symptoms of kidney cancer?
The most common sign of kidney cancer is blood in the urine, a painless condition called hematuria. This sign of renal cell carcinoma occurs in about 60 percent of patients. Bear in mind, however, that hematuria can also indicate many noncancerous conditions, such as kidney stones, kidney infections or benign tumors.
Other warning signals of kidney cancer include: low back pain; a mass or hard lump in the belly; unexplained weight loss; fatigue; recurrent fevers (not stemming from an infection); persistent pain in the side; swelling of the ankles and legs; low red blood cell counts (anemia); and high blood pressure. These signs and symptoms can also be caused by less serious conditions. However, if you notice any of them, it is important to see your doctor for an evaluation as soon as possible.
Unfortunately, kidney cancer frequently goes undiagnosed (or misdiagnosed) until it has already metastasized (spread). Because so many people over age 40 suffer from back pain, for example, this symptom of kidney cancer is often ignored. At the time of diagnosis, 15–25 percent of people with kidney cancer have metastatic disease.
What tests are used to diagnose kidney cancer?
If kidney cancer is suspected, the doctor will use several methods to diagnose the disease. First, the doctor will question the patient about his or her medical history and perform a physical exam, which will include feeling the abdomen for irregular masses. A urine sample will likely betaken and sent to a laboratory to detect small amounts of blood not visible to the naked eye or to rule out an infection. The doctor may also order another urine test called cytology, in which urine cells are examined under a microscope to find actual cancerous cells.
Blood tests to detect conditions sometimes associated with kidney cancer may also be ordered. These conditions include anemia (too few red blood cells), polycythemia (too many red blood cells due to the production by some types of kidney tumors of a hormone that steps up red blood cell production by the bone marrow), and hypercalcemia (high blood calcium levels).
One or more imaging tests to produce pictures of the kidneys and surrounding organs may also be performed. These tests may include: ultrasonography (ultrasound), which uses sound waves to generate images of the targeted area; computed tomography (CT scan), which is a specialized x-ray procedure in which x-rays are put together by a computer to create detailed cross-sectional images of the body; and magnetic resonance imaging (MRI), in which images are produced using strong magnets and radio waves instead of x-rays.
In addition, intravenous pyelography (IVP) may be done to help determine the extent of the damage to the kidney caused by a tumor. IVP is a procedure in which a series of x-rays are taken after a special dye is injected into the bloodstream. The dye travels in the blood to the kidneys, where it outlines the kidneys and nearby organs, such as the ureters and bladder, giving the doctor a clearer picture of the areas potentially affected by cancer.
Another common imaging test is arteriography, an x-ray procedure for examining blood vessels. Like IVP, it uses a contrast dye, but the dye is injected directly into the artery that supplies blood to the kidney. Arteriography can highlight the blood vessels that feed a kidney tumor, allowing doctors to develop a more precise surgical strategy to remove the tumor.
Once kidney cancer is diagnosed, imaging tests are performed to determine the extent of the disease. This is called staging. The stage of a cancer is the most significant factor when devising a treatment plan. In addition to the imaging studies described above, imaging tests that help doctors determine how far the cancer has spread include chest x-rays to check if the cancer has spread to the lungs and bone scans to check whether the cancer has spread to the bones.
What are the stages of kidney cancer?
For renal cell carcinoma, there are two staging systems that can be used to describe the extent of the disease: the TNM system (also known as the American Joint Committee on Cancer, or AJCC, system) and the Robson Staging System. Both classify the cancer using Roman numerals from I through IV (1–4). The higher the stage number, the more the cancer has spread and the more serious the disease.
The TNM system is used far more often than Robson classification. It is based on three main variables. The “T,” which stands for tumor, is followed by a number ranging from 1 to 3, and this indicates the tumor size and the extent by which the tumor has invaded nearby tissues. (Higher T numbers mean a bigger tumor or more extensive spread into surrounding tissues.)
The “N,” which is followed by a number from 0 to 2, indicates whether the cancer has spread to nearby lymph nodes (small collections of immune system cells that help fight infections) and how many lymph nodes contain cancer. And the “M,” followed by a 0 or 1, tells whether the cancer has spread to distant organs in the body or to lymph nodes not located near the kidney.
How is kidney cancer treated?
Treatment of kidney cancer depends on the type of tumor and the stage of the disease, as well as the patient’s age and overall health.
Surgery is the primary form of treatment for kidney cancer.Most often, a procedure known as radical nephrectomy is done. Radical nephrectomy involves removal of the entire kidney, as well as the adrenal gland (a gland that rests on the upper end of each kidney) and some surrounding fatty tissue and nearby lymph nodes.
Can a person live with only one kidney?
Yes. Despite the fact that the kidneys are extremely important, our bodies only need less than one complete kidney to survive.Today, thousands of Americans are living healthy lives with just one kidney. Some people have no working kidneys, but even they can survive with the aid of dialysis (a specially designed process to filter the blood).
Another type of surgery, partial nephrectomy, is used to treat smaller renal cell tumors. This technique involves removal of only the part of the kidney that contains the cancer. It is used in patients who have cancer in both kidneys, have only one kidney, or have a very small tumor.
Sometimes a procedure known as arterial embolization, which blocks the artery that feeds blood to the kidney (renal artery), is performed before surgery. A catheter (thin tube) is inserted into an artery in the groin and threaded through the blood vessel until it reaches the renal artery. Small pieces of a special gelatin sponge are then injected through the catheter to clog the renal artery. The goal is to kill some of the cancer cells and to reduce bleeding during the operation. In patients who cannot have surgery, arterial embolization may be used as a form of therapy.
Radiation therapy, in which high-energy rays are used to kill cancer cells, may also be used to treat kidney cancer, either before surgery to shrink the tumor or after surgery to destroy any remaining cancer cells. For advanced cancer, radiation therapy may also be used to relieve symptoms of pain or bleeding. In addition, radiation is sometimes used as the main form of therapy in patients whose overall health is too fragile to undergo surgery.
The type of radiation therapy used in treating kidney cancer is external beam radiation therapy, which means the radiation is administered from a machine, and the procedure is a lot like having an x-ray.
Although radiation is useful in treating many types of cancers, renal cell carcinomas do not respond particularly well to the therapy. So, although radiation therapy is a treatment option for kidney cancer, it is not routinely recommended.
Chemotherapy, the use of cancer-killing drugs, is sometimes given in addition to surgery for kidney cancer. But, like radiation therapy, chemotherapy is not very effective in treating renal cell carcinoma. Researchers are currently studying new anti-cancer drugs and new drug combinations to improve chemotherapy’s effectiveness.
Immunotherapy, also called biological therapy, is the newest form of treatment for kidney cancer. In recent years, it has become a standard treatment for metastatic renal cell cancer. Immunotherapy is a method of inducing the body’s own natural immune defenses to fight cancer. For metastatic renal cell cancer, it involves administering drugs called cytokines, which are proteins that stimulate the immune system. The two cytokines used most often are interleukin-2 (IL-2) and interferon-alpha. Studies have shown that both of these cytokines cause renal cell cancers to shrink by more than 50 percent in about 20 percent of patients. New research also suggests that combining IL-2, interferon and chemotherapy is promising.