Published on October 22, 2020
Genetic Factors Tied to Higher Rates of Leukemia in Hispanic Children
Hispanic children have the nation's highest incidences of acute lymphoblastic leukemia (ALL) and poorer outcomes overall, despite significant advances in understanding and treating childhood ALL and a dramatic improvement in the five-year survival rate (about 90%).
The reason for the higher incidence among Hispanic children appears to be genetic, according to Dr. Sara Zarnegar-Lumley, an assistant professor of pediatrics at Vanderbilt University in Nashville, Tennessee, who specializes in the care of children with leukemia.
When Hispanic children develop ALL, their disease is more likely to carry poor-risk genetic mutations, which means it is more difficult to treat, she said.
According to the Centers for Disease Control and Prevention’s Morbidity and Mortality Weekly Report (MMWR), from 2001 to 2014, the overall incidence of pediatric ALL was 34.0 cases per 1 million people; among Hispanics, it was 42.9 per 1 million.
An analysis of the data published in May 2015 found that the difference was greatest among older children: Hispanic children aged 15 to 19 years were 1.71 times as likely to be diagnosed with ALL as non-Hispanic children. The authors noted the ethnic disparity was only observed in childhood ALL and not present in other childhood cancers.
“As we learn more about the underlying biology of ALL and the genetic factors that predispose children to develop ALL, there is increasing evidence that this higher incidence in Hispanic children is due to a genetic predisposition to develop the disease,” she said in an email to Patient Power. She added that other potential factors include infectious or environmental exposures.
“Importantly, we also know that the survival outcomes in ALL are worse for Hispanic children, including increased risk of relapse,” she said.
What are the Treatment Risks for Hispanic Children with Acute Lymphoblastic Leukemia?
A study published in October 2018 in Clinical Cancer Research found that Hispanic children with ALL were twice as likely as non-Hispanic patients to develop neurotoxicity during methotrexate chemotherapy. Methotrexate is a standard component of ALL treatment. Neurotoxicity was defined as altered mental status, stroke, or seizure due to treatment.
Of 39 patients who developed neurotoxicity, nine experienced a second neurotoxic event, all of whom were Hispanic. Patients who developed neurotoxicity received on average 2.25 fewer doses as a result, which could lead to reduced treatment effectiveness.
“In general, leukemia looks a bit different among Hispanic patients,” said study author Dr. Michael E. Scheurer in an interview with Healio. Dr. Scheurer is an associate professor of pediatrics at Baylor College of Medicine and director of the Epidemiology Center at Texas Children’s Cancer Center in Houston.
“They have different types of mutations in the DNA of their leukemia cells than other patients. The disease biology is a bit different, and that could contribute to a higher rate of neurotoxicity.”
Dr. Zarnegar-Lumley said certain treatment-related toxicities occur more frequently in Hispanic children possibly because of co-occurring diseases. For example, Hispanic children are at greater risk for obesity and metabolic diseases than other ethnic groups; obesity puts children at greater risk of steroid-induced side effects.
Those side effects may impact treatment adherence, which has been shown to lower among Hispanic children and adolescents, particularly during the maintenance phase. The phase, which consists of oral chemotherapy for a prolonged period, is critical to maintaining remission.
The Roles of Early Detection and Access to Care
Dr. Zarnegar-Lumley said more studies are needed to understand the genetic link between ALL and the higher incidence among Hispanic children. She emphasized that early diagnosis and access to treatment are critical to improving outcomes.
“Generally speaking, lower socioeconomic status and decreased access to consistent healthcare are associated with inferior health outcomes in pediatric cancer patients,” she said.
“Unfortunately, Hispanic children in the United States are more likely to be a part of this demographic. These children are less likely to enroll in clinical trials at academic centers. We know when children with cancer are treated on large cooperative group clinical trials, their outcomes are better.”
She reiterated the importance of affordable access to healthcare for children, including primary and subspecialty care.
“We also need to provide culturally inclusive patient care and education to promote patient self-advocacy in a complex medical system should language or culture be an obstacle to care.”
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