Kidney Cancer

Kidney cancer happens when certain cells in the kidney grow and divide too quickly. Instead of dying off like normal cells, these abnormal cells build up and form a lump, called a tumor. Some tumors stay small and do not spread, but others can grow larger and move into nearby tissues or travel to other parts of the body. This process is called metastasis.

Most kidney cancers begin in the tiny filtering units inside the kidney, called tubules. These tubules normally clean the blood and make urine. When cancer starts here, it is called renal cell carcinoma (RCC), the most common type of kidney cancer in adults.

Kidney cancer is often found in just one kidney, but it can develop in both kidneys in rare cases. It is also different from cancers that begin elsewhere and later spread to the kidney, those are called secondary, or metastatic, cancers.

While kidney cancer is a serious disease, many people are diagnosed early when the cancer is still limited to the kidney. This makes treatment more effective and increases the chances for recovery.

Kidney cancer does not always cause symptoms in the early stages. Many people are diagnosed when the cancer is found by accident during imaging tests for another health issue. As the cancer grows, you may notice:

• Blood in the urine (the most common sign): Urine may look pink, red, or cola-colored. Sometimes the bleeding comes and goes.
• Pain in the back or side that does not go away: This may feel like a dull ache or a sharp pain on one side of the lower back.
• A lump in the side or lower back: You or your doctor may feel a mass in the area of the kidney.
• Fatigue: Feeling more tired than usual, even after resting.
• Unexplained weight loss: Losing weight without trying or changes in appetite.
• Fever that keeps coming back: Low-grade fevers that are not related to an infection or flu.
• Swelling in the ankles or legs: This may happen if kidney function is affected.
• Night sweats: Waking up with damp clothes or bedding.

Not everyone with kidney cancer will have all of these symptoms. Some people may have no signs at all until the cancer is more advanced.

Doctors do not always know why kidney cancer develops. Some people get it without having any known risks. Still, certain things can increase your chances:

• Smoking: Chemicals from tobacco can damage kidney cells and raise the risk of kidney cancer. The longer and heavier a person smokes, the higher the risk.
• Being overweight: Extra body weight can change hormone levels and increase the chance of tumors forming in the kidney.
• High blood pressure: People with long-term high blood pressure are more likely to develop kidney cancer, though doctors are still learning why.
• Family history of kidney cancer: Having a close relative (parent, brother, sister) with kidney cancer can raise your risk.
• Inherited conditions: Some rare health problems that run in families can make kidney cancer more likely. If kidney cancer runs in your family, your doctor may suggest genetic testing or regular checkups.
• Long-term dialysis treatment: People on dialysis for many years have a higher risk of kidney cancer, likely because of the way long-term kidney disease changes the cells.

Having one or more of these risk factors does not mean you will definitely get kidney cancer. It only means your chances are higher compared to someone without them.

There are several different kinds of kidney cancer. Knowing the type helps doctors choose the best treatment.

• Renal cell carcinoma (RCC): This is the most common type in adults. It starts in the tiny filters inside the kidney (tubules). Most people with kidney cancer have this type.
• Transitional cell carcinoma: This type starts in the area where the kidney meets the bladder, called the renal pelvis. It acts more like bladder cancer than kidney cancer.
• Wilms tumor: A rare type that mostly affects children, usually younger than age 5.
• Other rare forms: These include cancers like kidney sarcomas, which start in the kidney’s blood vessels or connective tissue.

Kidney cancer can cause problems both inside the kidney and in other parts of the body. Possible complications include:

• Spread of cancer (metastasis): Kidney cancer can move to other organs, most often the lungs, bones, or liver. When this happens, treatment usually becomes more complex.
• Kidney damage or loss of kidney function: Cancer in the kidney may reduce how well the kidney filters waste and balances fluids, salt, and minerals in the body. If one kidney is removed or stops working, the other kidney usually takes over.
• Blood problems: Kidney cancer can sometimes cause anemia (low red blood cell count), which may make you feel very tired or weak.
• High blood pressure: Changes in kidney function can lead to problems controlling blood pressure.
• Bone changes: If the cancer spreads to the bones, it can cause pain, weakness, or even fractures.
• General symptoms: Advanced cancer may cause weight loss, loss of appetite, or ongoing fatigue.

Not everyone will have these complications. Some people are treated before the cancer spreads or damages kidney function.

Contact your doctor or care team as soon as possible if you notice:

• Blood in your urine that is new or getting worse
• Sudden or severe pain in your side, back, or abdomen
• Trouble breathing, chest pain, or a persistent cough
• Swelling in your legs or ankles that appears quickly
• Extreme fatigue, weakness, or dizziness