What Is Kidney Cancer?

Kidney cancer, also known as renal cell carcinoma, is a type of cancer that starts in the cells of your kidneys—the two bean-shaped organs located on either side of your spine, just below the ribcage. These organs play a crucial role in filtering your blood, removing waste, and balancing fluids and electrolytes in your body.

This cancer usually begins when certain kidney cells grow uncontrollably and form a tumor. In adults, the most common type is clear cell renal cell carcinoma, though other types like papillary or chromophobe renal cancers can also occur. In children, a different form called Wilms tumor is more typical.

Early kidney cancer often doesn’t cause noticeable symptoms. It is frequently discovered by chance during imaging tests—like ultrasounds or CT scans—performed for other reasons. In some cases, symptoms such as blood in the urine, pain in the side or back, or an unexplained lump may lead to further investigation.

Known risk factors include smoking, obesity, high blood pressure, and certain inherited conditions. The condition is more common in men than women and typically affects people over the age of 60, though it can occur at younger ages as well.

Diagnosis is usually confirmed through imaging scans and, in some cases, a biopsy. Treatment depends on the size and stage of the tumor, and may involve surgery, immunotherapy, or targeted medications such as nivolumab or cabozantinib.

Many small, localized tumors can be completely removed with surgery. Early detection greatly improves the chance of a full recovery.

For context, kidney tumors can range in size from as small as 1 cm (about 0.4 inches) to more than 10 cm (about 4 inches) at the time of diagnosis. Understanding the risks and being alert to early warning signs can make a meaningful difference in outcomes.

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