What is kidney cancer?

Kidney cancer occurs when cells in the kidney grow out of control and form a tumor. The most common type — accounting for about 85% of kidney cancers — is renal cell carcinoma (RCC), which starts in the cells lining the small tubes inside the kidney.

Kidney cancer is the 6th most common cancer in men and 8th most common in women in the United States. The good news: when found early, it is often completely curable with surgery.

Risk factors

Smoking — Doubles the risk of kidney cancer. Quitting smoking reduces risk over time.
Obesity — Strongly associated with kidney cancer risk.
High blood pressure — An independent risk factor for kidney cancer.
Long-term dialysis — People who have been on dialysis for many years have a higher risk of developing kidney cysts and eventually kidney cancer.
Family history and genetics — Von Hippel-Lindau disease and other inherited conditions significantly raise risk.
Certain workplace exposures — Trichloroethylene and other industrial chemicals.

Symptoms

Early kidney cancer usually causes no symptoms at all — which is why many are found incidentally on CT or ultrasound scans done for other reasons. When symptoms do occur, they may include:

  • Blood in the urine (hematuria) — may be visible (pink/red urine) or found only on lab tests
  • Persistent pain in the side or back below the ribs
  • A lump or mass in the side or abdomen
  • Unexplained weight loss
  • Fatigue
  • Fever that comes and goes without infection
  • Loss of appetite
Blood in your urine — even if it happens once and goes away — should always be evaluated promptly. It's not always cancer, but it always warrants investigation.

Diagnosis and staging

Diagnosis typically involves CT scan or MRI to characterize the tumor, followed by a nephrectomy (surgical removal) which confirms the diagnosis. Biopsy before surgery is sometimes done but not always necessary.

Staging describes how far the cancer has spread:

  • Stage I & II: Tumor confined to the kidney — highly curable with surgery
  • Stage III: Spread to nearby lymph nodes or major blood vessels — often still treatable
  • Stage IV: Spread to distant organs — treatment focuses on controlling growth; newer targeted therapies and immunotherapy have significantly improved outcomes

Treatment

Surgery

The primary treatment for kidney cancer is surgical removal — either the entire kidney (radical nephrectomy) or just the tumor (partial nephrectomy, or nephron-sparing surgery). Partial nephrectomy is preferred when possible to preserve kidney function.

Active surveillance

For small tumors (under 3–4cm) in older or high-risk patients, careful monitoring with regular imaging may be appropriate rather than immediate surgery.

Targeted therapy and immunotherapy

For advanced or metastatic kidney cancer, drugs that target specific pathways (like sunitinib, pazopanib, cabozantinib) and immune checkpoint inhibitors (nivolumab, pembrolizumab) have transformed treatment outcomes in recent years.