Significant Portion of Pediatric NHL Cases Occur in Transplant Recipients

Pediatric solid organ transplant recipients account for about 3% of diagnosed pediatric non-Hodgkin lymphoma (NHL) cases in the United States, according to the results of a study published in Cancer.

“Although very few US children and adolescents have received a solid organ transplant, this population contributes a disproportionate fraction of pediatric NHL cases, especially DLBCL [diffuse large B-cell lymphoma] cases,” wrote Elizabeth L. Yanik, PhD, ScM, of Washington University School of Medicine in St. Louis, and colleagues. “This large contribution is due to the highly elevated risk of NHL after transplantation.”

According to the study, transplant recipients are at 100 to 200 times the risk for NHL compared with the general pediatric population. Although the rates of pediatric NHL are relatively low, Yanik and colleagues wanted to calculate the burden of transplant-related NHL in this population.

The researchers linked data from the US transplant registry and 16 cancer registries for people age ≤ 20 years between 1990 and 2012. They calculated cancer incidence rates for these transplant recipients and compared them with that of the general pediatric population.

During the time period from 1990 to 2012, there were an estimated 22,270 cases of NHL in US children and adolescents; 628 (2.82%) were in transplant recipients.

Although DLBCL only accounted for one-quarter of cases in the general pediatric population, 64.5% of transplant recipients had DLBCL. Burkitt lymphoma accounted for 8.6% of the transplant recipient cases.

“Immunosuppressant medications administered after transplantation are considered the primary cause of this increased risk, and reflecting this mechanism, most of the increase in the transplant population is from infection-related cancer,” the researchers wrote. “Remarkably, transplant recipients contributed 1 in 5 DLBCL cases diagnosed in children less than 5 years old and more than 1 in 10 cases across all ages in the most recent calendar years (2010–2012).”

The proportion of NHL cases among transplant recipients was highest in children younger than 5 years old (4.46%) and in the more recent calendar years from 2010 to 2012 (3.73%).

“This trend is driven by the rising prevalence of transplant recipients in the general population and not by increases in NHL risk among transplant recipients,” the researchers concluded. “It would be beneficial for a portion of future efforts in pediatric lymphoma research to focus specifically on transplant recipients because this unique group may require prevention and treatment approaches that differ from those for the general population.”