– Renal cell and clear cell adenocarcinomas account for 80% of kidney cancer. Other tumor types include transitional cell, squamous cell, and nephroblastoma.
Causes and Incidence
The cause of kidney cancer is unclear, but identifiable risk factors include use of tobacco products, acquired cystic disease, chronic irritation from renal calculi, exposure to petrochemical products, and radiation exposure. More than 18,000 new cases are diagnosed each year in the United States. About 20% of childhood malignancies and 2% of adult malignancies occur in the kidneys. The average age of diagnosis is 55 to 60, and men are affected twice as often as women.
Tumor cells, which most often originate in the renal parenchyma, grow into a well-defined tumor, often surrounded by perinephric fat, which slows infiltration of adjacent tissues. Metastasis occurs by venous or lymphatic routes, and the most common metastatic sites are the lungs, bones, liver, and brain.
Signs and symptoms develop late in the disease; hematuria is the most common presenting sign, followed by flank pain, a palpable abdominal mass, and/or fever of unknown origin.
The prognosis for metastatic lesions is poor because kidney tumors are resistant to radiation and chemotherapy. Complications include hypertension from pedicle compression.
Abdominal ultrasound and computed tomography scans help detect masses that warrant further diagnostic study. Biopsy by needle aspiration or tissue sample is definitive.
Nephrectomy with removal of regional lymph nodes.