Florida Institute of Research, Medicine & Surgery

Kidney Cancer
Kidney cancer accounts for about 2 to 3% of cancers in adults, affecting about 50% more men than women. Smokers are about twice as likely to develop kidney cancer as nonsmokers. Other risk factors include exposure to toxic chemicals and obesity. People affected are usually between 50 and 70 years of age. Most solid kidney tumors are cancerous, but fluid-filled tumors (cysts) generally are not. Almost all kidney cancer is renal cell carcinoma. Symptoms Blood in the urine is the most common first symptom, but the amount of blood may be so small that it can be detected only under a microscope. On the other hand, the urine may be visibly red. The next most common symptoms are pain in the flank (the area between the ribs and hip), fever, and weight loss. Infrequently, a kidney cancer is first detected when a doctor feels an enlargement or lump in the abdomen.
The red blood cell count may become abnormally high (polycythemia) because high levels of the hormone erythropoietin (which is produced by the diseased kidney or by the tumor itself) stimulate the bone marrow to increase the production of red blood cells. Symptoms of a high red blood cell count may be absent or may include headache, fatigue, dizziness, and visual disturbances. Conversely, kidney cancer may lead to a drop in the red blood cell count (anemia) because of slow bleeding into the urine. Anemia may cause easy fatigability or dizziness. Some people develop high levels of calcium in the blood (hypercalcemia), which may cause weakness, fatigue, slowed reaction times, and constipation.