In general the prognosis for patients with Wilms tumor isvery good. Prognostic factors include stage and histologic features. Anaplastic variants of Wilms tumor have a significantlyworse outcome than classic Wilms tumor. In addition LOH at chromosomes 1p or 16q confers an increased risk of relapseand death compared to tumors without LOH at either site.
The 4-year relapse-free survival of patients with tumors of favorable histologic picture is directly related to stage. Curerates for patients with localized Wilms tumor at diagnosis aregreater than 85%, whereas patients with pulmonary metastases have event-free survival rates of approximately 70% to 80%.
Sarcomas are divided into soft tissue sarcomas and bone cancers. Soft tissue sarcomas arise primarily from the connective tissues of the body, such as muscle tissue, fibrous tissue, and adipose tissue. Rhabdomyosarcoma, the most common soft tissue sarcoma in children, is derived from mesenchymal cells that are committed to skeletal muscle lineage. Less common soft tissue sarcomas include fibrosarcoma, synovial sarcoma, and extraosseous Ewing sarcoma. The most common malignant bone cancers in children are osteosarcoma and Ewing sarcoma. Osteosarcomas derive from primitive bone-forming mesenchymal stem cells. Ewing sarcomas are thought to be of neural crest cell origin.
The cause is unknown for most children diagnosed with sarcoma, although a few observations have been made regarding risks. Individuals with Li-Fraumeni syndrome (associated with a germline p53 mutation) and neurofibromatosis (associated with NF1 mutations) have an increased risk of softtissue sarcomas. There is a 500-fold increased risk for osteosarcoma for individuals with hereditary retinoblastoma. Prior treatment for childhood cancer with radiation therapy or chemotherapy, specifically alkylating agents, or both, increases the risk for osteosarcoma as a second malignancy.
In the United States, 850 to 900 children and adolescents under 20 years of age are diagnosed with soft tissue sarcomas each year; approximately 350 are rhabdomyosarcoma. The incidence of rhabdomyosarcoma peaks in children 2 to 6 years old and in adolescents. The early peak is associated with tumors in the genitourinary region, head, and neck; the later peak is associated with tumors in the extremities, trunk, and male genitourinary tract. Boys are affected 1.5 times more often than girls.
Of the 650 to 700 U.S. children and adolescents under 20 years of age diagnosed with bone tumors each year, approximately two thirds have osteosarcoma and one third have Ewing sarcoma. Osteosarcoma most commonly affects adolescents; the peak incidence occurs during the period of maximum growth velocity. The incidence of Ewing sarcoma peaks between ages 10 and 20 years but may occur at any age. Ewing sarcoma affects primarily whites; it rarely occurs in African American children or Asian children.
Available @ StudentConsult.com
The clinical presentation of rhabdomyosarcoma varies, depending on the site of origin, subsequent mass effect, and presence of metastatic disease. Periorbital swelling, proptosis, and limitation of extraocular motion may be seen with an orbital tumor. Nasal mass, chronic otitis media, ear discharge, dysphagia, neck mass, and cranial nerve involvement may be noted with tumors in other head and neck sites. Urethral or vaginal masses, paratesticular swelling, hematuria, and urinary frequency or retention may be noted with tumors in the genitourinary tract. Trunk or extremity lesions tend to present as rapidly growing masses that may or may not be painful. If there is metastatic disease to bone or bone marrow, limb pain and evidence of marrow failure may be present.