Kidney Tumors Committee

The membership of the Kidney Tumors Committee includes expertise in the following specialties: Pediatric hematology/oncology physicians, nurses, clinical research associates, biostatisticians, pathologists, pharmacists, radiation oncologists, diagnostic imaging, laboratory scientists, pediatric surgeons, urologists, and geneticists.

Progress

The National Wilms Tumor Study Group (NWTSG) was founded in 1969 and is one of the four research groups that merged in 2000 to become the Children’s Oncology Group (COG). About 70% of children with Wilms tumor in North America have participated in clinical trials over the past 20 years.  Additionally, children with other types of kidney cancer, including clear cell sarcoma of the kidney and malignant rhabdoid tumor, have participated in clinical research led by the NWTSG and COG.  Progress has varied according to the type of tumor:

Wilms tumor

The treatment of Wilms tumor is one of the great success stories of pediatric oncology.  Prior to cooperative research, only about 40% of children with Wilms tumor were cured. Today 85-90% are cured.  This progress has been achieved while reducing the amount of chemotherapy needed, and for two thirds of the children, eliminating the need for radiation therapy. This, in turn, has greatly reduced the long-term effects of treatment. The concept of improving the cure rate while decreasing treatments (now applied to much of CureSearch COG’s work) was pioneered in the study of Wilms tumor.

In addition to improving Wilms tumor therapy, NWTSG and COG researchers have uncovered important insights into the biology and genetics of Wilms tumor.  Several Wilms tumor genes have been discovered and new biological markers have been identified to predict those patients at greatest risk for tumor relapse.  One prognostic marker, called “loss of heterozygosity,” is being used in current COG trials to assign treatment.

Clear cell sarcoma of the kidney (CCSK)

Children with clear cell sarcomas of the kidney (CCSK) once had a 30-40% chance of survival; now 75-85% are cured. Although not recognizable as different from Wilms before removal of the tumor, CCSK requires a different and more intense combination of chemotherapy.

Malignant rhabdoid tumor

Malignant rhabdoid tumor occurs most commonly in the kidney and brain, but can arise in virtually any part of the body.   The COG Kidney Tumor Committee studies rhabdoid tumors outside the brain, while the COG Central Nervous System Tumor Committee studies rhabdoid tumors in the brain (also called atypical teratoid-rhabdoid tumors).   Rhabdoid tumor is one of the most aggressive and treatment-resistant pediatric cancers.  A specific gene mutation that leads to rhabdoid tumor was recently identified.  An increased understanding of rhabdoid tumor biology has created promising leads to improve treatment.

Renal Cell Carcinoma

Although not historically included in cooperative group trials, childhood renal cell carcinoma comprises approximately 6% of pediatric kidney tumors.  Research by COG investigators has identified important biological and clinical differences between adult and childhood renal cell carcinoma.

Current focus

A primary goal is to give only as much therapy to each child as is required, and no more. For groups with high cure rates, the research emphasis is on reducing treatments, which, in turn, will reduce long-term effects. For those with lower cure rates, the emphasis is on better treatments, which may be more toxic, but are the price for achieving a cure.

Low risk:

Researchers are exploring whether a small group of children with Wilms tumor have such a favorable prognosis that they may be cured with surgery alone – no chemotherapy or radiation.

Standard or intermediate risk:

This is the largest group of patients. The best way to cure these tumors is to continue studying them in the laboratory and clinically, and to work toward identifying the 10-15% whose tumors will recur.

Higher risk:

Some groups of patients have cure rates less than 75%.  These include those with Wilms tumor that has spread to distant sites, Wilms tumor with loss of heterozygosity, the anaplastic type of Wilms tumor, clear cell sarcoma with distant spread, and malignant rhabdoid tumor.  For these children, current research studies are testing more aggressive combinations of known chemotherapy drugs and new drugs that have shown promise in laboratory studies. 

Wilms tumor of both kidneys (bilateral Wilms tumor):

About 5% of children with Wilms tumor have the disease in both kidneys. These patients have special challenges, since treatment must not only cure the child, but also preserve kidney function. Researchers are working to improve the effectiveness of chemotherapy to shrink the tumor, and to refine the surgeries so that children are left with enough functioning kidney tissue.
 
Reviewed November 2008