Etiology

Incidence

Metastatic tumors

Localized tumors

Prognosis

With current treatment, the overall 5-year survival rate for patients with Ewing tumors that are still localized when they are first found is around 70%.

When the cancer has already spread at the time of diagnosis, the 5-year survival rate is about 15% to 30%. The survival rate is slightly better if the cancer has only spread to the lungs as opposed to having reached other organs.

Factors other than the stage of the cancer can also affect survival rates. Factors that have been linked with a better prognosis include:

• Smaller tumor size

• Main tumor is on an arm or leg (as opposed to chest wall or pelvis)

• Normal blood LDH level

• Good tumor response to chemotherapy

• Age younger than 10

Wilm`s tumor (Nephroblastoma)

Renal tumors account for 6.3% of cancer diagnoses for children younger than 15 years of age, with a reported incidence of 7.9 per million. Including adolescents younger than 20 years of age, this drops slightly to 4.4% of cancer diagnoses, with an incidence of 6.2 per million.

The five most common pediatric renal tumors are:

· Wilms' tumor (90-95%),

· clear cell sarcoma (6%),

· rhabdoid tumor (2%),

· congenital mesoblastic nephroma,

· nephroblastomatosis.

Wilms' tumor (also referred to as nephroblastoma or renal embryoma) is the most common primary malignant renal tumor of childhood and comprises 6% of all pediatric tumors.

Wilms' tumor (WT) typically occurs in children, rarely in adults. Its common name is an eponym, referring to Dr. Max Wilms, the German surgeon (1867–1918) who first described this kind of tumor.

WT affects about 1 in 10,000 live births. 60% present before the age of three years. Most nephroblastomas are unilateral, being bilateral in less than 5% of cases.

The majority (75%) occur in otherwise normal children; a minority (25%) is associated with other developmental abnormalities. It is highly responsive to treatment, with about 90% of patients surviving at least five years.

Genetic analysis of WT shows the chromosomes within the tumor cells to be normal, mutated, or mosaic. The relationship between Wilms' tumor and chromosomal mutations is based on the "two hit hypothesis" of Knudson. According to this model, individuals inherit a maternal and paternal set of chromosomes. Children with WT are born with a mutation in the tumor suppressor gene on one chromosome, thereby losing heterozygosity (LOH) at this locus (the first hit). Mutation at the same location on the other chromosome leads to tumor formation (second hit). Interestingly, studies of tumors with LOH show the vast majority are maternal. This tendency of LOH to favor the maternal or paternal allele is termed genomic imprinting. Somatic mosaicism has also been described in children with WT.

Several chromosomal deletions have been described in WT; the 11p13 gene has been named WT gene 1 (WT1); the 11p15 gene is called WT gene 2 (WT2); and the 16q gene has been named the WT gene 3 (WT3). The gene product of WT 1 is a DNA-binding protein found on fetal kidney and genitourinary tissues. The gene products of WT 2 and WT 3 are unknown.

The etiology of clear cell sarcoma, rhabdoid tumors and congenital mesoblastic nephroma are unclear.