ORLANDO – Ten-year overall survival and event-free survival were significantly higher in adolescents and young adults with acute myeloid leukemia who were treated with a pediatric regimen vs. an adult regimen, based on data from 517 patients aged 16-21 years.
Previous studies have shown improved survival in young adults with acute lymphoblastic leukemia who were treated with a pediatric regimen, said Dr. Anna R.K. Franklin of the University of Texas M.D. Anderson Cancer Center in Houston at the annual meeting of the American Society of Hematology. Dr. Franklin and her coauthors hypothesized that survival trends might be similar in acute myeloid leukemia patients.
The researchers compared 281 young adult patients with AML in Children’s Oncology Group (COG) trials, all of whom received a pediatric regimen, vs. 149 young adults in Cancer and Leukemia Group B (CALGB) trials and 87 young adults in Southwest Oncology Group (SWOG) trials, all of whom received an adult regimen. The patients were treated in 1986-2008.
Overall survival 10 years after study entry was 45% in the COG patients vs. 34% in the CALGB/SWOG patients (P less than .05). A subgroup analysis breaking down the combined population by age showed that overall survival after 10 years was 43% in younger patients (aged 16-18 years) vs. 32% in older patients (aged 19-21 years).
The median age was 18 years overall, but the median age in the COG patients was significantly younger than the median age in the CALGB/SWOG patients (17 years vs. 20 years).
The 10-year overall survival rates by age and group were 45% for younger COG patients, 44% for older COG patients, 40% for younger CALGB/SWOG patients, and 31% for older CALGB/SWOG patients.
Overall, the 10-year event-free survival rates were 39% for younger COG patients and 17% for older COG patients vs. 23%, and 22% for younger and older CALGB/SWOG patients, respectively.
In contrast, 10-year treatment-related mortality rates were significantly higher in COG patients than CALGB/SWOG patients. The rates were 26% for younger COG patients and 30% for older COG patients vs. a constant 12% for younger and older CALGB/SWOG patients.
In this study, age was a confounding variable that made comparison of patients on adult vs. child regimens difficult, because 94% of the COG patients were younger than 19 years, Dr. Franklin noted. However, "COG studies have significantly more [treatment-related mortality] and significantly less risk of relapse than the adult trials," she said.
Significant improvements occurred in 10-year overall survival, event-free survival, and relapse risk in more recent studies compared with earlier studies, but treatment-related mortality also increased, said Dr. Franklin. Multivariate analysis of the data is ongoing to determine which specific factors impact patient outcomes in adult vs. pediatric protocols, she said.
Dr. Franklin had no financial conflicts to disclose.