Although they comprise fewer than 1% of all gastrointestinal (GI) tumors, gastrointestinal stromal tumors (GIST) are the most common mesenchymal tumors of the GI tract. It has been estimated that there are 3,300 to 6,000 new GIST cases per year in the United States. A study based on Surveillance, Epidemiology and End Results (SEER) registry data found that the age-adjusted yearly incidence of GIST in the United States was 6.8 per million from 1992 to 2000. However, the...
The Children's Oncology Group (COG) protocols do not administer anthracycline during induction to patients with National Cancer Institute standard-risk precursor B-cell ALL. This three-drug induction regimen results in a complete remission rate of greater than 95% for standard-risk patients.
Patients treated by other study groups receive a four-drug induction regimen regardless of presenting features:
The most common four-drug induction regimen is vincristine, corticosteroid (either dexamethasone or prednisone), L-asparaginase, and either doxorubicin or daunorubicin. Some studies have suggested that this more intensive induction regimen may result in improved event-free survival (EFS) in patients presenting with high-risk features.[5,6] The COG reserves the use of a four-drug induction for patients with high-risk B-precursor ALL and T-cell ALL.
For patients who are at standard risk or low risk of treatment failure, four-drug or more induction therapy does not appear necessary for favorable outcome provided that adequate postremission intensification therapy is administered.[5,7,8]
Many current regimens utilize dexamethasone instead of prednisone during remission induction and later phases of therapy.
The Children's Cancer Group conducted a randomized trial comparing dexamethasone and prednisone in standard-risk ALL patients.
The trial reported that dexamethasone was associated with a superior EFS.
Another randomized trial was conducted by the United Kingdom Medical Research Council.
The trial demonstrated that dexamethasone was associated with a more favorable outcome than prednisolone in all patient subgroups.
Patients who received dexamethasone had a significantly lower incidence of both central nervous system (CNS) and non-CNS relapses than patients who received prednisolone.
Other randomized trials did not confirm an EFS advantage with dexamethasone.[11,12]
The ratio of dexamethasone to prednisone dose used may influence outcome. Studies in which the dexamethasone to prednisone ratio is 1:5 to 1:7 have shown a better result for dexamethasone, while studies using a 1:10 ratio have shown similar outcomes.