Kidney Cancer – Causes, Signs and symptoms

Kidney Cancer

Also called: Hypernephroma, Renal Cell Cancer, Kidney Adenocarcinoma

Reviewed By:
Martin E. Liebling, M.D., FACP
Mark Oren, M.D., FACP


Kidney cancer occurs when cells in these organs grow uncontrollably and invade other cells. Kidney cancer represents 2 percent of cancers in the United States, according to the U.S. Centers for Disease Control and Prevention (CDC).

The kidneys are two bean-shaped organs that are located in the upper back portion of the abdomen. The kidneys lies on each side of the spine. The kidneys filter toxins from the bloodstream and eliminate waste products from the body as urine. The kidneys also serve other functions such as maintaining blood pressure, modifying levels of salt and water and producing several vital hormones. People have two kidneys but can function with one. If both kidneys fail or are removed, kidney function can be taken over by dialysis, medical machines that function as artificial kidneys.

Many types of tumors form in the kidneys, including several noncancerous types. The major types of kidney cancer include renal cell carcinoma and transitional cell carcinoma. These types of carcinomas occur mostly in adults. Children rarely get kidney cancer. When they do, it is usually a type called Wilms tumor.

The causes of kidney cancer are unknown. However, several risk factors are closely associated with developing kidney cancer. They include smoking, obesity, high blood pressure, many years of kidney dialysis and certain hereditary conditions.

There are rarely any symptoms in the early stages of kidney cancer. As the tumor grows, blood in the urine (not always visible to the patient) can be found in a urine test. Weight loss, back pain, fatigue and loss of appetite may be present. Kidney cancer that has spread to other organs and tissues can produce additional symptoms.

Diagnosis of kidney cancer usually involves obtaining a medical history, physical examination, blood testing and urine testing. Imaging tests (e.g., CAT scan, ultrasound) may be used to determine the size and spread of the cancer if the disease is suspected. A biopsy may be taken to diagnose the cancer cell type and the stage of the cancer.

Treatment is most successful when the kidney cancer is detected early and when it can be removed surgically. If the cancer spreads or cannot be completely removed with surgery, chemotherapy and/or radiation therapy may be used, but these are not standard treatment options. Other treatments, such as biological therapy (immunology used to enhance the immune system attack on cancer cells) produce better results.

Kidney cancer can recur after treatment and it may return to the same location or reappear in other sites in the body. Depending on the site of recurrence, surgery may be a treatment option to remove the cancer.

About kidney cancer

Kidney cancer results from the malignant transformation of kidney cells that grow uncontrollably and eventually invade healthy cells. It can affect one or both kidneys. Sometimes the cancer cells cause kidney structures to become misshapen and interfere with their ability to function properly.  Over time, these tumors can spread (metastasize) to local and distant tissues and organs, complicating the condition and its treatment.

Cancer that begins in the kidney, or primary kidney cancer,  is rare, representing only 2 percent of cancers in the United States, according to the U.S. Centers for Disease Control and Prevention (CDC). Cancer can spread to the kidneys from another area of the body, such as the prostate or liver.

The kidneys are two bean–shaped organs that are located in the upper back portion of the abdomen, on each side of the spine. The kidney’s main function is to eliminate toxins and waste from the blood and concentrate it into urine. From the kidneys, urine travels through tubes called ureters to the bladder, where it is stored until urination. 

Other kidney functions affect many other body systems. The kidneys are also responsible for:

  • Maintaining appropriate levels of water and salt in the body

  • Producing the hormone renin, which monitors blood pressure

  • Producing the hormone erythropoietin, which regulates production of the body’s red blood cells

Kidney tumors can be benign (noncancerous) or malignant (cancerous). While there are many types of kidney cancers, renal cell carcinoma is by far the most common. It accounts for more than 90 percent of kidney cancers, according to the American Cancer Society (ACS).

Most kidney cancer patients are diagnosed between 50 and 70 years of age. It is rare for children and young adults to develop this disease. Additionally, kidney cancer is more prevalent among men than women. Two-thirds of cases affect men, and almost twice as many men die from the disease than women according to the ACS.

The ACS estimates that there will be 38,890 new cases of kidney cancer in the United States in 2006 and the disease will result in 12,840 deaths. The five-year survival rate for kidney cancer is over 90 percent when the disease is detected in the earliest stage.

Types and differences of kidney cancer

There are several types of malignant kidney cancers, according to the American Cancer Society (ACS). The most common type is called renal cell carcinoma, which account for more than 90 percent of kidney cancers. These tumors in the tubules of the kidney usually appear as one mass. However, there may be more than one mass and they may be in both kidneys. Renal cell carcinomas may be divided into five subtypes.

Other types of cancerous kidney tumors include:

  • Transitional cell carcinoma. Also called urothelial carcinoma, this type of cancer begins in the area of the kidney that stores the urine and in the ureters, which drain urine from the kidneys. This less common form of kidney cancer is similar to bladder cancer. It may occur in the kidneys, bladder or ureters, and treatment is the same regardless of its location.
  • Wilms tumor (nephroblastoma). Cancer cells that originate in the embryonic kidney cells and represent 5 to 6 percent of kidney cancers, according to the ACS. It occurs mostly in children, and rarely affects adults. The most common kidney cancer among children, Wilms tumor has a strong hereditary component. 
  • Renal sarcoma. A rare form of kidney cancer that affects the connective tissue of the kidney.

In addition, several types of benign tumors may develop in the kidneys. These include renal adenomas, oncocytomas and angiomyolipomas.

Risk factors and causes of kidney cancers

The causes for most cases of kidney cancer are unknown. Cells that become cancerous grow uncontrollably, although physicians are uncertain what initiates this growth. Certain types of kidney cancer may be traced to specific risk factors or genetic conditions. Risk factors increase the likelihood of developing a specific disease. However, they do not indicate that a person will definitely develop the disease. Some risk factors are out of a person’s control and some involve choices that can be altered. Risk factors associated with renal cell carcinoma, the most common form of kidney cancer,include:

  • Smoking. Smoking increases the risk for kidney cancer by 40 percent, according to the American Cancer Society (ACS). The longer a person smokes, the greater his or her cancer risk. Individuals who quit smoking have a reduced risk of developing the disease.
  • High blood pressure (hypertension). Studies have shown that high blood pressure is linked to renal cell carcinoma. Additionally, individuals with high blood pressure and obesity, another kidney cancer risk factor, may be three times more likely to develop the disease, according to the ACS. Kidney cancer risk decreases with controlled blood pressure. However, individuals with high blood pressure are often prescribed blood pressure-lowering medications, and it is difficult to determine if the increased cancer risk stems from the condition or the medication.
  • Obesity, dietand inactivity. Obesity, high fat diets and/or sedentary lifestyles have also been linked with kidney cancer. In fact, some physicians believe that obesity is a contributing factor in 20 percent of kidney cancer cases. Some specific diet elements may also contribute to kidney cancer. A recent study showed that diets high in cereals, breads and pasta may increase kidney cancer risk.
  • Age. Most individuals are between 50 and 70 years of age when they are diagnosed with kidney cancer. Children and young adults rarely have this disease.
  • Gender. Renal cell carcinoma affects men almost twice as often as women, according to the ACS.
  • Occupational and environmental toxins. Studies show that asbestos, cadmium, trichloroethylene and other, similar substances common to certain professions and in the environment have been linked to increased kidney cancer risk.
  • Dialysis. This is a process by which a machine performs the functions of the kidneys for people whose kidneys are not functioning properly. Individuals with a history of prolonged use of dialysis have an increased risk of developing kidney cancer, but it is unclear whether this is related to dialysis or the type of kidney injury that caused the kidney failure. People who have had a kidney transplant and those who take immunosuppressant drugs are also at increased risk of developing kidney cancer.
  • Radiation exposure. Radiation exposure has been linked to kidney cancer. Women who have had radiation for uterine problems are at a higher risk of developing the disease. However, these causes are relatively rare circumstances.
  • Prior kidney cancer. People who have had cancer in one kidney are at increased risk of developing a cancer in the other kidney.

Genetic and hereditary risk factors of renal cell carcinoma include:

  • Family history. Patients with a family history of renal cell carcinoma are more likely to develop the disease, especially if a sister or brother has been previously diagnosed with the condition.
  • Von Hippel-Lindau (VHL) disease. This hereditary disease may cause patients to develop several different types of tumors. Though in many cases these tumors are benign, between 25 and 45 percent of individuals with VHL disease develop renal cell carcinoma (typically the clear cell variety), according to the ACS. 
  • Hereditary papillary renal cell carcinoma. A hereditary condition that may cause patients to develop one or multiple papillary renal cell carcinomas. Individuals with this condition do not have the other medical issues associated with VHL disease.
  • Hereditary renal oncocytoma. People with this condition have an inherited tendency to develop kidney tumors known as oncocytomas. However, it is important to note that these masses are typically benign.

Risk factors such as smoking and environmental exposure to toxins may also affect other types of kidney cancer, such as transitional cell carcinoma. Patients with bladder cancer also have an increased risk of transitional cell carcinoma.

Signs and symptoms of kidney cancer

Signs and symptoms of kidney cancer do not typically appear until the later stages of the disease. Blood in the urine (hematuria) is the most common sign that the kidneys are undergoing a disease process. The blood may or may not be observed by the patient. However, a urine test may show even trace amounts. Other signs and symptoms of kidney cancer may include:

  • Abdominal pain
  • Kidney or abdominal mass
  • Anemia (low red blood count)
  • Loss of appetite or unexplained weight loss
  • Bone pain
  • Fever (low-grade)
  • Edema (swelling) of the legs and ankles
  • Intestinal obstruction
  • General malaise and fatigue
  • Pain in metastatic sites

Unusual signs of kidney cancer may include:

  • Hypercalcemia (excess calcium in the blood
  • Hypertension (high blood pressure)
  • Abnormal liver tests
  • Polycythemia (excess red blood cells)

Patients exhibiting any of these symptoms should see their physician. The above symptoms may indicate any number of less serious conditions and diagnostic tests are needed to determine their exact cause.

The childhood kidney cancer called Wilms tumor usually does not have symptoms, even in its later stages. This condition is usually found during a routine physical examination of the child’s abdomen.

Diagnosis methods for kidney cancer

Diagnosis of kidney cancer typically begins with a medical and family history and a physical examination to detect tumor masses and lumps. A number of diagnostic procedures may be used to determine if it a tumor is malignant and whether it has spread to other areas of the body (metastasized). Tests used to detect and diagnose kidney cancer may include:

  • Blood and urine tests. Laboratory tests performed on samples of blood or urine. These tests can determine a chemical or hormonal imbalance that may indicate disease in the organs. These tests may include:
    • Complete blood count (CBC). A blood test that measures red blood cells, white blood cells and platelets. Either anemia (low red blood cell count) or erythrocytosis (high red blood cell count) may indicate abnormalities in kidney function. For instance, too much erythropoietin (a hormone produced by the kidney) elevates the production of red blood cells.
    • Urinalysis(urine testing). Blood in the urine is the most common sign of kidney cancer. Cancer cells may sometimes be discovered in the urine of kidney cancer patients. Urinalysis is typically more effective in detecting transitional cell carcinoma than renal cell carcinoma.
    • Calcium tests. A blood test that shows abnormal calcium levels in the blood. The kidneys are partially responsible for maintaining proper calcium levels. High calcium levels may indicate kidney problems.
    • Enzyme test. A blood test that detects levels of enzymes that indicate whether the liver and kidneys are functioning properly. Liver enzymes produced in abnormal amounts may indicate damage to the liver or bone, which may be a sign of metastasis.
  • Needle biopsy. A thin needle is used to extract tissue from the tumor and observed under a microscope to check for cancer cells. Needle biopsies are not commonly used to diagnose kidney cancer, but may be used to confirm it if imaging tests are inconclusive, or to check for tumor spread.

Imaging tests may be used to determine the size and location of the tumor and whether it has spread to other areas of the body. These may include:

  • Ultrasound. Uses sound waves to create images of tumors.
  • CAT scan (computed axial tomography). Images are taken of the body from different angles to locate tumors in the body. Dye may be injected or ingested by the patient to help identify growths in the kidneys.
  • MRI (Magnetic resonance imaging). Magnetic waves and computerized technology are used to create cross-sectional images the body to help detect abnormalities, including tumors.
  • Positron emission tomography (PET) scan. A radioactive labeled sugar is injected into the bloodstream and is rapidly absorbed by the cancer cells, making them detectable to a camera that creates an image of the tumors.
  • Intravenous pyelograms (IVPs). Contrast dye injected into the bloodstream travels through the kidneys, ureters and bladder and x-ray images are taken.
  • X-rays. Use low doses of radiation to create images of organs in the body. A chest x-ray is taken to show if there are masses in the lungs and bones in the chest cavity. These x-rays may identify metastasis to these areas, which may occur in the later stages of kidney cancer.
  • Bone scan. Radioactive material injected into the bloodstream collects in the bones, where it is detected by a scanner. Bone scans are typically used to determine if the cancer has spread from the initial site to the bones.
  • Venography. A dye is injected into the inferior vena cava (a major vein) and x–rays are taken to determine the spread of cancer to the renal vein and the vena cava.
  • Angiography. A contrast dye is injected into the renal artery (which feeds the kidney), making the blood vessels in the kidney visible. X-rays are taken of the visible vessels. This procedure may be used in diagnosis of kidney cancer, but is more commonly used in planning surgical treatments because of the details captured.
  • Cystoscopy. For transitional cell cancer detected in an IVP, a cystoscope (long narrow tube) is inserted into the bladder through the urethra. The tube contains a light and a lens and allows the physician to view the urethra and bladder and remove small tissue samples for biopsy.

Treatment options for kidney cancer

Diagnosis and treatment of patients with kidney cancer is delivered by a team of healthcare professionals called a cancer care team. Specialists on this team may include:

  • Urologist (urinary tract specialist)
  • Medical oncologist
  • Radiation oncologist
  • Surgeon
  • Pathologist

Early detection of kidney cancer is important for a good prognosis (outlook). In almost half of the cases diagnosed, the cancer has not spread outside of the kidneys, and the tumor can be surgically removed. In another 25 percent of the patients, the cancer has spread to only nearby organs and in the remaining 25 percent of cases, it has invaded distant sites, according to the American Cancer Society (ACS).

More advanced cases of kidney cancer – especially those that have spread to other parts of the body – require more extreme treatment measures. The patient’s age, general health condition and the extent of the metastasis assist physicians in determining the treatment path with the best possible outcome. Treatment options for kidney cancer include:

  • Nephrectomy. Surgical removal of one or both kidneys. Surgery can have an exceptional outcome depending on the stage of the disease. If the tumor metastasizes to a single site, a nephrectomy may be beneficial. However, if the tumor metastasizes to multiple sites, nephrectomy is not recommended because it does not improve the patient’s survival rate. Surgery also helps to prevent other complications of disease. The following surgical procedures may be used to treat kidney cancer:
    • Radical nephrectomy. Removal of the kidney, the adrenal gland and surrounding fat and lymph nodes. Radical nephrectomies have a high cure rate. This is the most commonly performed surgery to treat renal cell carcinoma, according to the ACS.
    • Partial nephrectomy. Also called nephron sparing surgery, partial nephrectomy is the surgical removal of the tumor and any affected surrounding kidney tissue. Partial nephrectomies allow patients to retain some kidney function. These surgeries are usually performed when both kidneys are affected, or when a patient only has one kidney and it becomes cancerous. More of these surgeries are now performed on individuals with very small renal tumors (less than 4 centimeters or 1 3/4 inch) in one kidney.
    • Simple nephrectomy. Removal of the entire kidney, but no surrounding tissue or related organs. It is possible to survive and live a normal life with the one remaining kidney. If that kidney should also become diseased, people can survive by using dialysis, which acts as an artificial kidney. Dialysis is performed regularly to cleanse the blood of toxins, eliminate the toxins and restore the cleansed blood to the body. People have survived for years using dialysis treatment.
  • Surgical removal of metastases. Approximately 25 percent of patients have metastatic spread of renal cell carcinoma at the time of diagnosis, according to the ACS. The surgical removal of the metastases may sometimes help alleviate symptoms, such as pain. However, it does not usually improve the patient’s chance of survival and is only recommended when there are only one or a few metastases that are easily accessible.
  • Arterial embolization. Artificial blockage of an artery. This procedure may be used to cut off blood supply and nourishment to a tumor in cases where surgery is not possible. During artificial embolization, a catheter is inserted through an incision into the main blood vessel that leads to the patient’s kidney. Small pieces of a special gelatin sponge are then injected into the blood vessel. The sponge clogs the blood vessel and starves the cancer cells of oxygen and other vital nutrients.
  • Biological therapy (also called immunotherapy). Use of biological agents such as interferons and interleukins to enhance the immune system to fight against the cancer cells. Certain forms of biological therapy also work by directly attacking the cancer cells. Biological therapy has shown good results in treating kidney cancer and has been successful in curing some patients. It can be used alone or with other treatments such as surgery.
  • Antiangiogenesis compounds. These substances block the growth of new blood vessels that the cancer needs to grow and survive. Some of these compounds are now used regularly to treat kidney cancer.
  • Hormone therapy. Pills or injections of hormones to stop cancer growth in certain cancers. Physicians will sometimes prescribe this treatment but success has been limited with this therapy.
  • Chemotherapy. Use of powerful drugs to kill cancer cells and to prevent them from spreading. Kidney cancer cells are resistant to chemotherapy and it is not commonly used to treat this disease although research is ongoing. Chemotherapy is primarily used for later stage metastases and for recurrent renal cell carcinoma.
  • Radiation therapy. Use of precise radiation beams focused to kill or shrink tumor cells. Kidney cancer is not very responsive to radiation therapy. Use of radiation therapy before or after surgery is not typically recommended because it has shown no increase in survival rates. Radiation therapy is usually used for palliative treatment in all stages of kidney cancer and for later stage metastases.
  • Clinical trials. A physician may recommend participation in a clinical trial that will test new experimental treatments. For instance, clinical trials are currently studying the effect of stem cell transplants on kidney cancer. During a transplant, donated stem cells (immature blood cells) are infused into the blood to restore the patient’s blood supply. This is done to enhance the immune system to fight the cancer and to restore blood cells. Generally, patients in the advanced stages of kidney cancer seek to participate in such trials because of the limitations of standard treatments. Clinical trials are conducted for all stages of kidney cancer. Patients are encouraged to consult their physician regarding the benefits and risks of participating in clinical trials.

Prevention methods for kidney cancer

Many of the risk factors for kidney cancer cannot be controlled. However, there are some lifestyle changes that may help reduce the chances of developing the disease, including:

  • Quit smoking. Smoking increases the risk of kidney cancer by 40 percent, according to the American Cancer Society (ACS).
  • Exercise. Exercise lowers blood pressure and helps patients lose weight. High blood pressure is a risk factor for kidney cancer. Studies have shown that those who exercise regularly are less likely to develop this disease.
  • Diet and weight. Obesity is linked to a high risk of developing kidney cancer, although recent studies have shown that obese kidney cancer patients have less aggressive kidney tumors. Patients can maintain a healthy weight by exercising and making dietary modifications, such as lowering their fat intake and reducing consumption of other foods that may affect the risk of kidney cancer.
  • Avoid occupational and environmental toxins. Heavy metals, asbestos, cadmium and aniline dyes should be avoided because they increase the risk of developing kidney cancer. 

Ongoing research regarding kidney cancer

Ongoing research is being conducted to discover new ways to detect, prevent and treat kidney cancer. Some of the studies currently being conducted focus on:

  • Gene testing and gene therapy to identify genetic predispositions and to correct genetic problems leading to cancer.

  • Immunotherapy to boost the natural immune system, such as monoclonal antibodies and the development of tumor vaccines, which use the tumor cells to create a patient-specific vaccine.

  • Targeted therapies, such as better antiangiogenesis drugs to inhibit cancer cell growth by blocking blood vessel growth in tumors and antigrowth factor drugs to inhibit cell growth.

  • Improvements to surgical techniques.

  • Bone marrow and peripheral blood stem cell transplant techniques.

Staging kidney cancer

The prognosis (predicted outlook or chance of survival) of kidney cancer depends on cancer stage or how widespread it is in the body. Generally, the earlier a cancer is diagnosed, the better the patient’s prognosis (outlook for recovery). Early stage cancers typically respond better to treatment and have not spread (metastasized) to other parts of the body.

The American Joint Committee on Cancer (AJCC) has developed a more detailed staging system used by physicians. This involves:

  • “T” describes the extent of cancer growth. For instance, TX indicates tumor cannot be assessed and T0 indicates no evidence of tumor is observed. T1 and T2 indicate the cancer is confined to the kidney. T3a and T3b indicate that surrounding tissue but not vena cava are cancerous. T3c indicates the vena cava and its wall have cancer cells. T4 indicates the cancer is extending further beyond the region of the kidneys and its surrounding fascia (connective tissue).

  • “N” describes the extent of regional lymph node involvement. NX indicates regional lymph nodes cannot be assessed and N0 indicates regional lymph nodes are cancer free. N1 indicates there is cancer in one regional lymph node. N2 indicates there is cancer in more than one regional lymph node.

  • “M” describes the extent of distant metastasis. MX indicates metastasis cannot be assessed and M0 indicates that distant lymph nodes and organs are cancer free. M1 indicates that cancer has spread to distant lymph nodes and organs.

Stages of kidney cancer are:

  • Stage I. The tumor is confined to the kidney and is smaller than 7 centimeters (2–3/4 inches).

  • Stage II. Tumor is confined to the kidney and is larger than 7 cm (2-3/4 inches).

  • Stage III. Cancer cells have invaded:

    • The kidney and one nearby lymph node; or

    • The adrenal gland and/or fatty tissue that surrounds the kidney, and may have spread to one nearby lymph node; or

    • The kidney’s main blood vessels and may have spread to one nearby lymph node

  •  Stage IV. Cancer cells have spread:

    • Beyond the fatty tissue that surrounds the kidney and may have spread to one nearby lymph node; or

    • To at least two nearby lymph nodes; or

    • To other organs, including the pancreas, bowel or lungs, and may have invaded nearby lymph nodes

  • Recurrent. Kidney cancer that has returned after it was treated. It may return many years later to the kidney or other parts of the body.

Another staging system called the Robson staging system exists. However, this system is older than the TNM staging system and less often used.

Prognosis for kidney cancer is very good if the tumor remains in the kidney and can be completely removed by surgery. Half of kidney cancer cases can be treated with surgery. With proper treatment, the five year survival rates for kidney cancer, according to the American Cancer Society (ACS), are:

Stage5-Year Survival Rate
I95 percent
II80 percent
III43 to 66 percent
IVLess than 10 percent

Questions for your doctor about kidney cancer

Preparing questions in advance can help patients have more meaningful discussions with their physicians regarding their conditions. Patients may wish to ask their doctor the following questions about kidney cancer:

  1. What tests can be used to determine if I have kidney cancer?
  2. What type of cancer do I have?
  3. What stage is my cancer?
  4. What are my treatment options?
  5. What are the benefits and risks of the treatments?
  6. Will surgery remove all of my kidney cancer?
  7. Can I survive with one kidney?
  8. What are the chances the cancer will spread to another area?
  9. What are the chances that my cancer will return?
  10. Can any lifestyle changes help prevent a cancer reccurrence?
  11. If my cancer is genetic, will my children be at higher risk for kidney cancer?
  12. Can you refer me to some support groups?
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