Kidney cancer ranks thirteenth in frequency among all cancers and accounts for about 3% of all human malignant tumors. There were about 31,200 new cases of kidney cancer diagnosed in 1998 in the United States, and 11,900 deaths that year
were attributed to kidney cancer (in the U.S.).(1)  Between 1973 and 1990, the incidence of kidney cancer in the United States has increased by 35.4%.(2)  This increase may be due in part to improved diagnostic tests.  Better radiological techniques (including CT, MRI and ultrasounds) allow more sophisticated examinations in the evaluation of patients who present a variety of abdominal symptoms.  Furthermore, 25-30% of renal tumors are diagnosed as an incidental finding due to more widespread use of such testing..
 
 

    Renal cell carcinoma (RCC), the most common type of kidney cancer in adults, accounts for about 85% of all kidney tumors.  Nephroblastoma (i.e. Wilms' tumor) accounts for 5-6%, transitional cell neoplasms of the renal pelvis account for 7-8% and the rest are various sarcomas of renal origin.(3)

    Renal tumors are solid, usually pseudoencapsulated masses with satellite tumor nodules occurring in 10 to 16 percent of patients.  They show no preference as to intrarenal site and occur bilaterally in 1% of patients. Based on cytoplasmic apperance, four distinct patterns of tumor have been identified: clear in approximately 25% of cases, granular in 12%, mixed in 50% and spindle-sarcomatoid in 14%.  Patterns of tumor growth include nonpapillary (85% of cases) and papillary (10% of cases).(4)

    In both nonpapillary and papillary renal cancers, malignant cells arise from the epithelium of the proximal renal tube.  Nonpapillary disease may be subdivided by cell type, being either clear cell, granular cell, mixed clear and granular cell, or more rarely, sarcomatoid.  Papillary adenocarcinomas, representing 5-15% of all renal carcinomas, are relatively avascular and are associated with a 5-year survival rate of 85% compared to 52% for nonpapillary carcinomas.(5)

    Wilms' tumor is the most common type of kidney cancer in children; it is a nephroblastoma and is distinct from renal cell carcinomas. It is a rapidly progressive kidney tumor of childhood with peak incidence between the ages of one and two. Wilms' tumor occurs in a heritable and a nonheritable form. The heritable form is frequently bilateral.  The cure rate is now almost 90%; however, patients with the heritable disease appear to be at risk for second tumors.  The tumors are typically multi-lobed, bulging, and gray-tan in color. Growth in renal veins is less common than in renal cell carcinoma. (4)

    Sarcomatoid renal cell cancer is a distinct pathologic variant of RCC, defined histologically by the highly pleomorphic spindle cells and/or giant cells resembling sarcoma, along with a varying degree of clear or granular epithelial cells that typify RCC.  It is an uncommon renal malignancy. It is locally aggressive and potentially metastatic, and it responds poorly to immunotherapy.  Surgical resection alone does not seem to affect the course of the disease because the tumors are usually metastatic or locally advanced by the time they are diagnosed.(6)
 
 

* overuse of painkillers containing phenacetin (not available in US for over 20 years)
* exposure to cadmium (cadmium may also increase the cancer-causing effect of smoking)
* obesity or diet high in fat
* hypertension
* use of certain diuretics
* von Hippel-Lindau syndrome (disease caused by gene mutation in the VHL gene), may be familial
* tuberous sclerosis patients
* patients who have been on dialysis for a long time may develop cysts in their kidneys that can give  rise to renal cell cancer
* coke-oven workers and asbestos workers have higher rates of kidney cancer
* males have twice the risk of females
* cigarette smokers have twice the risk of non-smokers
* renal cell carcinoma is found mostly in adults 50-70; it is rare in children and young adults(1) (2)(7)

    Kidney cancer is usually detected when a person has some sign of a problem.  The most common sign of kidney cancer is blood in urine. Other symptoms are a lump in kidney area, dull ache or pain in the back or side.  Some people experience high blood pressure, an abnormal number of red blood cells, tiredness, rapid weight loss, fever, swelling of ankles and legs, or high blood pressure.  Since all of these symptoms can be caused by other medical problems, diagnosis by a physician is important if the symptoms are present.
 
 

    The kidneys need to be seen in order to identify cancer or show kidney damage caused by the tumor.  There is no standard blood test for the disease.  An image of the kidneys can be obtained with X-rays of kidneys involving injected dyes,   CT (computed tomography) scans, MRIs (magnetic resonance imaging), arteriograms, or  ultrasound exam. A biopsy is needed to confirm the diagnosis.
 
 

    Although tumor size is not always a reliable index of metastatic potential, early renal carcinomas often represent a malignancy of low grade.  The disease spreads by direct extension to adjacent structures or through lymph or blood to distant sites.  Distant metastases remain the primary cause of death and therapeutic failure. Growth is relatively silent until late in the development of the cancer, so metastases are fairly common.  Approximately 20-40% of patients have metastases at the time of diagnosis.  Of these 70% are limited to one organ, 40-50% involve the lungs; 22%, bone; 20%, lymph nodes; and 8-15%, other organs. (5) (10)
 
 

I- tumor is confined within the kidney capsule
II- tumor invades through the renal capsule but is confined with Gerota's fascia
III- tumor has invaded the regional lymph nodes, ipsilateral renal vein or inferior vena cava
IV- documentation of distant metastases or involvement of adjacent organs other than the ipsilateral adrenal gland8

 
 
 
 
 

Survival rates

Cumulative Relative Survival Rates Five Years After Diagnosis of Kidney Cancer, 1985-1988

Surgical treatment had the best 5-year relative survival rates.  Patients less than 50 years old had improved prognosis compared with patients older than 50.  This reflects the diagnosis of neproblastoma as a form of kidney cancer with an improved prognosis compared with renal cell adenocarcinomas and other kidney cancers.(9)