Kidney Cancer & Kidney Masses

Most kidney tumors are now found incidentally on scans done for something else — and small ones have excellent outcomes.

Usually found by accident

The majority of kidney tumors today are discovered incidentally, on a CT or ultrasound ordered for an unrelated reason. That is genuinely good news: incidentally found tumors are typically small, confined to the kidney, and highly curable.

The classic textbook triad of flank pain, a mass, and blood in the urine is now uncommon and generally indicates advanced disease.

Not every mass is cancer

Simple kidney cysts are extremely common and almost always harmless. Cysts are graded by the Bosniak system, which sorts them from clearly benign to clearly concerning. Angiomyolipomas are benign fat-containing tumors that usually need only monitoring, though large ones can bleed. Oncocytomas are benign but hard to distinguish from cancer without tissue.

When the picture is unclear, a kidney biopsy can be useful. It is safe and increasingly used, particularly when the result would change management.

Treatment options

Active surveillance is a legitimate option for small masses, especially in older patients or those with other significant medical problems. Small tumors typically grow slowly, and monitoring avoids intervention that may never be needed.

Partial nephrectomy removes the tumor and preserves the rest of the kidney. It is preferred whenever technically feasible for smaller tumors, because retaining kidney function has meaningful long-term consequences for cardiovascular health.

Radical nephrectomy removes the entire kidney and is used for larger or centrally located tumors. Most people function well with one kidney.

Ablation — freezing or heating the tumor through a needle — is an option for small tumors, especially in patients who are poor surgical candidates. Advanced disease is treated with immunotherapy and targeted agents, which have improved outcomes considerably in recent years.