What Is Kidney Cancer? Types, Symptoms, Risk Factors, Diagnosis, and Treatment
Kidney cancer is a disease in which abnormal cells in the kidney grow out of control and form a tumor. It most often starts in the small tubes of the kidney that help filter blood and make urine. The most common type is renal cell carcinoma, often shortened to RCC.
Prefer a visual summary? View our Kidney Cancer Infographic for a quick overview of the key facts, symptoms, diagnosis, and treatment.
Kidney Cancer Key Facts
Kidney cancer is a disease in which abnormal cells in the kidney grow out of control and form a tumor.
Renal cell carcinoma, often called RCC, is the most common type of kidney cancer in adults.
Clear cell renal cell carcinoma is the most common subtype of renal cell carcinoma.
Early kidney cancer often causes no symptoms and is sometimes found by chance during an ultrasound, CT scan, or MRI done for another reason.
Possible symptoms include blood in the urine, pain in the side or back, unexplained weight loss, tiredness, fever, or a lump in the abdomen.
Risk factors include smoking, obesity, high blood pressure, long-term dialysis, older age, male sex, family history, and certain inherited conditions.
Treatment depends on the stage and type of kidney cancer. Options may include surgery, active surveillance, ablation, immunotherapy, targeted therapy, or radiation therapy in selected cases.
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| Illustration of two kidneys, with one normal kidney and one cutaway kidney showing a kidney tumor inside the organ.Custom medical illustration. © Chris Morais |
What Is Kidney Cancer?
The kidneys are two bean-shaped organs located deep in the back part of the abdomen, one on each side of the spine as explained in the article Where Are the Kidneys Located? Their main job is to filter waste products and extra fluid from the blood and remove them from the body as urine. They also help control blood pressure, support red blood cell production, and maintain the balance of salts and minerals in the body. These functions are detailed in the post What Do the Kidneys Do? Main Functions Explained in Simple Terms.
Kidney cancer begins when cells in the kidney develop genetic changes that allow them to grow and divide in an uncontrolled way. These cells can form a mass, also called a tumor. Some kidney tumors remain within the kidney for a long time, while others can grow into nearby tissues or spread to other parts of the body.
Kidney cancer is more common in adults than in children. It is usually diagnosed in older people, often after the age of 60, and it is more common in men than in women. Many kidney cancers are found before they cause symptoms, often during an ultrasound, CT scan, or MRI done for another reason.
Common Types of Kidney Cancer
The most common type of kidney cancer is renal cell carcinoma. Renal cell carcinoma accounts for most adult kidney cancers and usually begins in the lining of small tubes within the kidney. These tubes are part of the kidney’s filtering system.
Clear cell renal cell carcinoma is the most common subtype of RCC. Under the microscope, the cancer cells often look pale or clear because of the way fat and other substances are stored in the cells. This is the type most people are referring to when they talk about the common form of kidney cancer.
Papillary renal cell carcinoma is another important subtype. It is less common than clear cell RCC and often forms small finger-like structures when seen under the microscope. Some papillary kidney cancers behave slowly, while others may be more aggressive depending on their features.
Chromophobe renal cell carcinoma is less common than clear cell and papillary RCC. The cells often look larger and paler under the microscope. In many cases, chromophobe RCC has a better outlook than some other kidney cancer types, especially when found early, although any kidney cancer requires proper assessment and follow-up.
Rare Types of Kidney Cancer
Not all cancers found in or near the kidney are renal cell carcinoma. Urothelial carcinoma of the renal pelvis starts in the part of the kidney where urine collects before moving into the ureter. This is different from renal cell carcinoma and is more closely related to cancers of the bladder and urinary tract.
Wilms tumor is a kidney cancer that mainly occurs in children. It is very different from adult kidney cancer and is diagnosed and treated in a different way.
Renal sarcoma is a very rare kidney cancer that begins in the connective tissue or blood vessels of the kidney rather than in the kidney tubules. Because it is uncommon, treatment usually requires specialist assessment.
There are also rare inherited forms of kidney cancer. In some families, kidney cancer can occur because of inherited genetic conditions. These may lead to kidney tumors at a younger age or tumors in both kidneys.
Benign Kidney Tumors and Cysts
Not every kidney growth is cancer. Many kidney cysts are benign, especially simple renal cysts, which are often found incidentally during scans. These usually do not spread and may not need treatment unless they cause symptoms or have unusual features.
Oncocytoma is a benign kidney tumor that can sometimes look like kidney cancer on imaging. Because it can be difficult to tell the difference before surgery, doctors may recommend careful monitoring, biopsy, or removal depending on the situation.
Angiomyolipoma is another non-cancerous kidney tumor made up of blood vessels, muscle, and fat. Small angiomyolipomas may only need monitoring, but larger ones can sometimes bleed and may need treatment.
The key point is that a kidney mass is not always cancer, but it should be properly assessed.
Symptoms of Kidney Cancer
Kidney cancer often causes no symptoms in its early stages. This is one reason many cases are found by chance during imaging tests done for back pain, abdominal symptoms, or other unrelated problems.
When symptoms do occur, one of the most important signs is blood in the urine. The urine may look pink, red, brown, or tea-colored. Sometimes blood is not visible and is only found on a urine test.
Pain in the side, back, or lower ribs can also occur, especially if the tumor grows larger. Some people may feel a lump or fullness in the abdomen or side, although this is less common today because many cancers are found earlier through scans.
Other possible symptoms include unexplained weight loss, tiredness, loss of appetite, fever without an obvious infection, and a general feeling of being unwell. These symptoms can happen for many reasons and do not always mean cancer, but they should not be ignored when persistent.
Risk Factors for Kidney Cancer
A risk factor is something that increases the chance of developing a disease. Having one or more risk factors does not mean a person will definitely get kidney cancer, and some people diagnosed with kidney cancer have no obvious risk factor.
Smoking is a well-known risk factor for kidney cancer. The risk is higher in people who smoke more, and stopping smoking can reduce the risk over time.
Excess body weight is also linked with kidney cancer. Obesity can affect hormones, inflammation, and metabolism in ways that may increase cancer risk.
High blood pressure is another important risk factor. Kidney cancer is more common in people with hypertension, although the relationship between blood pressure, kidney health, and medication history can be complex.
People who have long-term kidney failure and require dialysis have a higher risk of developing kidney cancer. Certain inherited conditions can also increase the risk, especially when kidney cancer occurs at a younger age, affects both kidneys, or runs strongly in the family.
Other possible risk factors include a family history of kidney cancer and exposure to certain workplace chemicals, depending on the type and duration of exposure.
How Kidney Cancer Is Diagnosed
Kidney cancer is often first suspected after an imaging test shows a mass in the kidney. This may happen during an ultrasound, CT scan, or MRI performed for another medical reason.
Once a kidney mass is found, doctors assess its size, appearance, location, and whether there are signs that it has spread. CT scans and MRI scans are commonly used to obtain more detailed information. Blood tests and urine tests may also be done to assess kidney function, anemia, and general health.
A biopsy may be recommended in some cases, especially when the diagnosis is uncertain or when the result would change treatment. However, not every kidney mass needs a biopsy before treatment. In many cases, imaging features and the overall clinical situation guide the next step.
Staging is an important part of diagnosis. Staging describes how large the cancer is, whether it has grown outside the kidney, and whether it has spread to lymph nodes or distant organs.
Treatment of Kidney Cancer
Treatment depends on the type of kidney cancer, the size and stage of the tumor, whether it has spread, the function of the kidneys, and the person’s overall health.
Surgery is often the main treatment for kidney cancer that is confined to the kidney. A partial nephrectomy removes only the tumor and a small amount of surrounding tissue, preserving as much kidney as possible. A radical nephrectomy removes the whole kidney and sometimes nearby tissues, depending on the situation.
For small kidney tumors, especially in older people or those with other health problems, active surveillance may be considered. This means the tumor is monitored closely with regular scans rather than treated immediately.
Ablation treatments, such as freezing or heating the tumor, may be used for selected small kidney cancers when surgery is not suitable.
For advanced kidney cancer, treatment may include immunotherapy, targeted therapy, or a combination of treatments. These medicines are designed to help control cancer that has spread beyond the kidney or has a higher risk of returning. Radiation therapy is not usually the main treatment for kidney cancer, but it may be used in certain situations, such as relieving pain or treating cancer that has spread to specific areas.
Disclaimer: This is for informational purposes only. For medical advice or diagnosis, consult a professional.
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