Risk stratification of rhabdomyosarcoma: a moving target.

Known prognostic factors for rhabdomyosarcoma include primary site, stage, group (amount of tumor remaining after initial surgery before chemotherapy), lymph node involvement, age, and histology. These factors are taken into account when determining risk stratification for treatment allocation, with some differences between the European and U.S. approaches. The relationship of fusion status for PAX-3 of PAX-7 FOXO1 to outcome has been analyzed by a number of groups, but many of the studies are troubled by problems inherent in the use of convenience cohorts and the fact that patients in the analyzed groups are not always treated in a uniform fashion. One recent study analyzed outcome of patients treated in a similar fashion on the same protocol and found that patients with alveolar histology who were fusion negative had an outcome similar to those with embryonal histology. This article reviews many of the studies surrounding fusion status and outcome, risk stratification issues, and outcome of risk groups. The time is rapidly approaching in which fusion status will be used to allocate therapy for rhabdomyosarcoma.