About 90 percent of kidney cancers are a type called renal cell carcinoma, which usually forms a single tumor in one of the person’s two kidneys.
- What is kidney cancer?
- Types of kidney cancer
- Risk factors
- How common is kidney cancer?
- Next steps
What is kidney cancer?
Kidney cancer starts in the kidneys, a pair of organs that lie in the back of your abdomen. Each is about the size of a fist.
- Your kidneys make urine by removing waste and extra water from your blood.
- They also make substances to help control blood pressure and to make red blood cells.
- At the top of each kidney is an adrenal gland. A layer of fatty tissue and an outer fibrous tissue surround the kidney and adrenal gland.
While kidneys are important, you actually need less than one complete kidney to function. Some people who do not have any working kidneys survive with the help of dialysis — using a specially designed machine that filters their blood.
Types of kidney cancer
There are four types of kidney cancer — renal cell carcinoma (RCC), transitional cell carcinoma, Wilms tumor and renal sarcoma.
Renal cell carcinoma
RCC accounts for about 90 percent of kidney cancers. It arises from the lining of the tiny tubules inside your kidney that filter your blood and make urine.
Usually it grows as a single mass within a kidney. Occasionally there are two or more tumors in one kidney or even tumors in both kidneys at the same time.
There are several subtypes of RCC, including:
- Clear cell — the most common form, affecting about 70 percent of people with RCC. It is associated with another condition called von Hippel-Lindau syndrome.
- Papillary kidney cancer — which accounts for about 10 percent of RCC cases. It is associated with hereditary papillary RCC, hereditary leiomyomatosis and RCC syndromes.
- Chromophobe renal cell carcinoma — a rare type, accounting for about five percent of cases. Birt-Hogg-Dube syndrome, a specific genetic mutation, is associated with chromophobe RCC.
- Collecting duct renal cell carcinoma — which is very rare.
- Translocation renal cell carcinoma — which is rare but increasing. It appears in late adolescence and young adulthood.
- Unclassified renal cell carcinomas — which don’t fit into any of the other categories or may have more than one type of cell. They often include aggressive tumors that don’t respond well to traditional therapies for RCC.
Transitional cell carcinoma
Transitional cell carcinomas account for five to 10 percent of all kidney cancers. Also known as urothelial carcinoma, this type of cancer does not start in the kidney but in the renal pelvis (where urine goes before it enters the ureter). Learn more in our bladder cancer section.
Wilms tumor, also known as nephroblastoma, almost always occurs in children. Learn more about childhood kidney cancer on Seattle Children’s website.
Renal sarcoma is the most rare kidney cancer and accounts for just one percent of all kidney cancer cases. It is treated like other sarcomas.
Symptoms of kidney cancer
Kidney cancers often don’t cause symptoms in the early stages.
When symptoms do occur, they may include:
- Blood in your urine
- Low back pain on one side
- A mass or lump on the side or lower back
- Loss of appetite
- Weight loss
- Recurrent fevers not associated with colds or flu
- Swelling of your ankles and legs
Conditions other than cancer may cause the same symptoms as kidney cancer. If you have any symptoms that concern you, talk to your doctor.
Diagnosing kidney cancer
If your doctor suspects you may have kidney cancer, they will do a physical exam to look for signs of the disease and ask about your symptoms, medical and family history and risk factors.
You might also have any or all of these tests:
- Biopsy — to remove cells and examine them under a microscope, both to diagnose cancer and identify the type of cell involved, which is important in planning treatment
- Genetic tests — to look for gene mutations if you have relatives who were diagnosed with kidney cancer, especially at a younger age, or who have a genetic condition that is a risk factor for kidney cancer
- OncoScan CGAT — a new chromosome genomic array test at SCCA that can help identify genetic changes useful in diagnosing kidney cancer, determining the subtype, understanding the risk of recurrence and outlook for survival and guiding therapy decisions
- Imaging tests — such as ultrasound, intravenous pyelogram (IVP), computed tomography (CT) scan or magnetic resonance imaging (MRI) scan to help find out whether a suspicious area is cancerous or to determine if cancer has spread
- Blood tests — to check the number of blood cells, electrolytes and enzyme levels, which may identify abnormalities caused by kidney cancer
Stages of kidney cancer
Staging is the process of finding out how far cancer has spread within the tissue where it started or to other parts of the body. The treatment that your doctor recommends will be based, in large part, on the stage of your cancer.
There are two types of staging for kidney cancer:
- Clinical stage — your doctor’s best estimate of the extent of your disease, based on the results of your exam, lab tests and imaging studies
- Pathological stage — based on the same factors as your clinical stage, plus what is found during surgery, if you have surgery, and examination of the removed tissue
Kidney cancer is assigned an overall stage of I, II, III or IV, with IV being the most advanced.
Risk factors for kidney cancer
Risk factors for kidney cancer include:
- Age — The risk of kidney cancer increases as you age. Kidney cancer is uncommon before age 45. It occurs most often in people 55 or older. The average age at diagnosis is 64.
- Sex — RCC is about twice as common in men as in women.
- Smoking — Smokers are twice as likely to get kidney cancer as nonsmokers.
- Obesity and diet — Being overweight and having a high-fat diet increase your risk.
- Exposure to certain environmental substances — Asbestos, cadmium and organic solvents are among the substances that raise kidney cancer risk.
- Genetic and hereditary factors — Having kidney disease or a family history of kidney cancer puts you at greater risk.
- High blood pressure — Risk for kidney cancer is elevated in people with high blood pressure.
- Race — For reasons that are unclear, African-Americans have a slightly higher rate of RCC.
Several hereditary syndromes that result from a faulty gene increase kidney cancer risk:
- Von Hippel-Lindau syndrome
- Birt-Hogg-Dube syndrome
- Hereditary papillary RCC
- Hereditary leiomyomatosis and RCC syndrome
People with Lynch syndrome may also be at greater risk.
How common is kidney cancer?
Kidney cancer is among the 10 most common cancers in both men and women. Each year about 65,000 people in the United States are diagnosed with the disease.
While the rate of people diagnosed with kidney cancer has been slowly rising since the 1970s, the death rate has been slowly declining since the 1990s.
- Request an appointment to see an SCCA kidney cancer expert.
- Learn about kidney cancer treatment at SCCA.
- Read stories of people who've had kidney cancer.
- Find resources and support for new SCCA patients.