June 5, 2014 | by Nicole White
A quarter of children in remission from acute lymphoblastic leukemia, or ALL, are tripling their risk of a relapse because they are missing too many doses of an essential maintenance medication, according to findings from a recent City of Hope study.
The research, published in the journal Blood, also reports maintenance medication adherence was lower in minority groups. About 46 percent of African-American children and 28 percent of Asian children are not taking enough doses to prevent relapse, compared with 14 percent of white children.
Acute lymphoblastic leukemia, a cancer of the white blood cells, is the most common form of childhood cancer. While more than 95 percent of children with ALL enter remission within a month of receiving initial cancer therapy, one in five will relapse. Additionally, relapsed disease is often harder to treat and may involve costlier, most toxic therapies.
In order to remain cancer-free, children in ALL remission must take a form of oral chemotherapy, called 6-mercaptopurine(6MP), every day for two years to protect against the disease coming back.
Despite 6MP’s proven benefit, previous studies have suggested pediatric ALL patients have difficulty taking it consistently. Other studies reported survival rates vary greatly among racial groups – prompting investigators to begin studying race-specific patterns of adherence in children with ALL.
“While we don’t yet know why children of different races have significantly different survival rates for ALL, we know that their adherence to their maintenance medication is a critical factor in their survival,” said first author Smita Bhatia, M.D., M.P.H. “With this in mind, we sought to explore the potential linkages that may exist between several key race-specific sociodemographics of these children and their adherence to 6MP.”
Bhatia, who is also the Ruth Ziegler Chair in Population Sciences, and her team began their research studying differences in medication adherence among different racial groups of children in remission from ALL in 2012, reporting that Hispanic children did not follow their prescribed maintenance regimen as consistently as non-Hispanic whites. To examine the differences in medication compliance among African-American, Asian and non-Hispanic white children, the team enrolled 298 patients from 77 institutions in a study tracking 6MP levels in the blood, questionnaire responses from patients and families, and records from a pill bottle that electronically tallies each date and time the bottle was opened for a period of six months.
Of all three groups, the African-American children took their medication the least often, with 46 percent of them taking 90 percent or less of their medication. This is the threshold at which risk of relapse becomes significant. While the Asian children in the study group took their medication more consistently, 28 percent of them did not take at least 90 percent of their medication. Non-Hispanic white children were more adherent to their maintenance therapy regimen than any other group; however, 14 percent still did not take enough to meet researchers’ criterion for drug adherence.
In total, about 25 percent of the children enrolled in the study did not take their medication at least 90 percent of the time, tripling their relapse risk.
Regardless of race, families reported that the most common reason for children not taking their 6MP medication was forgetfulness.
“These results are the basis for further studies that will examine how physicians can successfully intervene — using technology, for example — to ensure that children do not experience an increased risk of relapse because they did not take their oral chemotherapy,” Bhatia said.
Learn more about City of Hope's Department of Population Sciences.