Kidney Cancer, from the CureRays guide library.

Kidney cancer forms in the filtering organs of the urinary system; many are found early by chance on scans and cured with surgery — and precise radiation is a newer option.

What it is.

The kidneys are two bean-shaped organs that filter waste from the blood into urine. Kidney cancer usually begins in the tiny tubes that do this filtering. Because early kidney cancer rarely causes symptoms, many tumors are discovered by accident when a scan is done for another reason — and at that stage they are often small and curable. Kidney cancer has long been considered resistant to ordinary radiation, but modern high-precision stereotactic radiation is changing that for patients who cannot have surgery.

How radiation treats it.

Radiation uses focused high-energy x-rays to damage cancer-cell DNA so the cells can no longer divide. Kidney cancer was long thought to resist radiation, but stereotactic body radiation therapy delivers a much larger dose per session, with image guidance and breath-motion management keeping the beams locked on the tumor while sparing the rest of the kidney and nearby organs. Treatments are painless and brief; side effects are usually mild, such as temporary fatigue or nausea, and most kidney function is preserved.

The ways we can treat it.

Stereotactic body radiation therapy (SBRT). Delivers a few very high, precise doses that overcome kidney cancer's usual radiation resistance, controlling the primary tumor in over 90% of cases for patients who cannot have surgery.

SBRT for oligometastases. Focused radiation can ablate a small number of spots where kidney cancer has spread — to bone, lung, or elsewhere — often delaying the need to change drug therapy.

Palliative radiation. Short courses relieve pain or other symptoms from kidney cancer that has spread, especially to bone.

Questions we hear often.

My kidney tumor was found by accident — is that bad? Often it is actually good news. Incidentally found kidney cancers tend to be small and early, when cure rates are highest.

I heard radiation doesn't work on kidney cancer — is that still true? That was the old view with conventional radiation. Modern stereotactic radiation (SBRT) uses much higher, focused doses that effectively control kidney tumors, and it is a real option when surgery is not.

Will I be able to live with one kidney? Yes. Most people function normally with one healthy kidney, which is why surgeons preserve as much kidney as possible whenever they can.

This guide is informational only. It is not medical advice — please confirm anything here with your care team.