Among children with favorable-histology Wilms’ tumors, those with loss of heterozygosity at chromosomes 16q and 1p appear to have a worse prognosis, according to a study published in the Journal of Clinical Oncology.
Wilms’ tumor is a rare childhood cancer of the kidney that affects roughly 500 children in the U.S. each year. Survival is generally quite good, with more than 90% of children surviving for at least four years after diagnosis. Treatment often involves surgery and chemotherapy and may also involve radiation therapy.
Based on the appearance of the tumor cells, Wilms’ tumor is classified as having either favorable histology (associated with good prognosis) or anaplastic histology (associated with worse prognosis).
Information about changes in genes that potentially play a role in tumor growth or tumor control may also provide information about prognosis: children whose tumors show loss of heterozygosity-a situation where one chromosome has a normal copy of a gene and one chromosome has a mutant or deleted copy (at chromosomes 16q and 1p, for example) appear to have worse survival.
Loss of heterozygosity occurs at chromosome 16q in approximately 17% of Wilms’ tumor patients and at chromosome 1p in approximately 11% of Wilms’ tumor patients. Collecting additional information about factors that predict survival with Wilms’ tumor may help guide treatment decisions.
To test the relationship between loss of heterozygosity (LOH) at chromosomes 16q or 1p and survival among children with Wilms’ tumor, researchers evaluated 1727 patients with favorable histology and 182 patients with anaplastic histology, enrolled primarily from the U.S. and Canada.
Among children with anaplastic histology, the following results were recorded:
- There was no relationship between LOH and survival.
- Among children with favorable histology, LOH at both 16q and 1p appeared to identify a subset of children with significantly worse prognosis.
- Children with LOH at both of these locations and stage I or II cancer had a four-year survival rate of 91%, compared to 98% among children with LOH at neither of these locations.
- Among children with stage III or IV cancer, those with LOH at both locations had a four-year survival rate of 78% compared to 92% among children with LOH at neither location.
The researchers concluded that patients with favorable-histology Wilms’ tumor have a greater risk of relapse and death if their tumors show LOH at both chromosomes 16q and 1p. Information about LOH at these locations may help guide decisions about the optimal intensity of treatment.
Grundy PE, Breslow NE, Li S et al. Loss of Heterozygosity for Chromosomes 1p and 16q is an Adverse Prognostic Factor in Favorable-Histology Wilms Tumor: A report from the National Wilms Tumor Study Group. Journal of Clinical Oncology. 2005;23:7312-7321.
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