Kidney cancer signs and symptoms

The kidneys are two bean-shaped organs attached to the back wall of the abdomen and tucked underneath the ribs. Kidney cancer develops when cells there begin to grow in an uncontrolled way.

Kidney cancer is often difficult to detect in its early stages. In fact, before a tumor has grown or the disease has spread, kidney cancer is most commonly discovered by an X-ray or ultrasound performed for another reason.

Many factors contribute to this delayed diagnosis, including the location of the kidneys—deep inside the body, where small tumors are less likely to be seen or felt during a physical exam. Once the disease has grown or advanced beyond the kidneys—generally to nearby lymph nodes or to the lungs, bones or liver—signs are more likely to develop, but they’re often mistaken for less serious conditions.

Symptoms of kidney cancer

The most common sign of kidney cancer is blood in the urine (hematuria), which may appear rusty or dark red. Other signs of kidney cancer may include:

• Low back pain, or persistent pressure on one side
• Mass or lump on the side or lower back
• Unexplained weight loss
• Loss of appetite
• Night sweats
• Fatigue
• Testicle swelling (caused by enlarged veins near the testicle)
• Unexplained fevers that come and go
• Swelling of the legs or ankles
• High blood pressure
• Anemia (low red blood cell count)

Although these symptoms may indicate a kidney tumor, they also may be caused by other, less serious health issues. Some kidney cancer patients experience none of these signs, and others experience different symptoms entirely.

Early warning signs of kidney cancer

Before symptoms of kidney cancer are noticeable, a laboratory test or an imaging study may reveal a possible diagnosis.

For example, a routine urine test may find traces of blood that the naked eye can’t see. Signs of kidney cancer also may be detected during a computed tomography (CT) scan, which consists of X-rays taken at different angles and processed by a computer into 3D images. This imaging test may show a growth in the kidney—and may even be able to tell a noncancerous cyst from a solid cancer tumor if dye is injected into a vein beforehand.

Magnetic resonance imaging (MRI) produces detailed images of the kidneys using a computer and magnetic fields in place of X-rays. During an MRI, a dye called gadolinium may be used to increase tumor visibility.

Finally, an ultrasound uses sound waves to look for signs of a kidney tumor, and determine whether a mass in the kidney is a fluid-filled cyst or a solid tumor.