Kidney cancer is a malignant growth that develops in the tissues of the kidneys, most commonly arising from the lining of the small tubes within the organ in a form known as renal cell carcinoma. It often develops silently in its early stages and may be discovered incidentally during imaging for other conditions. When symptoms occur, they can include blood in the urine, persistent flank or lower back pain, a lump in the abdomen, fatigue, unexplained weight loss, or fever. Risk factors include smoking, obesity, high blood pressure, certain genetic conditions, and long-term kidney disease. Diagnosis typically involves imaging studies and sometimes biopsy, and treatment may include surgical removal of part or all of the kidney, targeted therapy, immunotherapy, or, less commonly, radiation or chemotherapy, depending on the stage and extent of spread.