Some Pediatric Transplant Patients May Have a Markedly Increased Cancer Risk

Children who have received solid organ transplants are at high risk of cancer, particularly non-Hodgkin’s lymphoma, according to a study in Pediatrics.

In the US Transplant Cancer Match study, data from the Scientific Registry of Transplant Recipients were linked to 16 state and regional cancer registries. Of approximately 40,500 solid organ transplants performed between 1987 and 2011 in patients younger than 18 years, 45% were in a region covered by one of the linked cancer registries./kidneynews/9_6/15/graphic/15f1.jpg

Counts of registry-observed cancers were divided by the counts that were to be expected from general population rates in order to calculate standardized incidence ratios (SIRs). The researchers than assessed patient characteristics associated with cancer risk. Because most of the observed cancers were non-Hodgkin’s lymphomas, risk factors for this cancer and combined cancers that did involve non-Hodgkin’s lymphoma were assessed separately.

The analysis included 17,958 transplants performed in 17,732 children and adolescents. About 44% of transplants were kidney transplants. A total of 392 cancers were diagnosed, and the median time from transplantation to diagnosis was 2.5 years. Non-Hodgkin’s lymphomas accounted for 71% of posttransplant cancers, with a median time to diagnosis of 1.6 years.

The incidence of non-Hodgkin’s lymphoma was greatly elevated among transplant recipients, compared to the general population, with a SIR of 212. Risk was also increased for Hodgkin’s lymphoma, which had a SIR of 19, and for leukemia, which had a SIR of 4. There was also a very large increase in myeloma risk, which showed a SIR of 229, although this was based on only 3 observed cases.

Other significant associations based on 8 or fewer cases included cancers of the kidney, thyroid, liver, testis, soft tissue, brain, bone and joint, ovary, skin (melanoma), bladder, breast, and vulva.

The risk of non-Hodgkin’s lymphoma was particularly high for children younger than age 5 at the time of their transplant; the associated SIR was 313. It was also high for those who were sero-negative for Epstein-Barr virus (EBV) at transplant, SIR 446; and for those who underwent intestinal transplantation, SIR 1280. Among the independent predictors of non-Hodgkin’s lymphoma incidence were first year posttransplant, hazard ratio (HR) 4.04; seronegative EBV status, HR 2.71; and induction immunosuppression, HR 1.31.

“Pediatric recipients have a markedly increased risk for many cancers,” the researchers write. They note that their study population is more than 20 times larger than in a previous Swedish study, which reported more than a 100-fold increase in cancer risk among pediatric transplant recipients.
Most posttransplant cancers are non-Hodgkin’s lymphomas, with the risk being highest in the first posttransplant year. The authors suggest that strong associations with immunosuppression and EBV infection suggest a cancer prevention opportunity, if EBV infection can be prevented or controlled.

References

1. Yanik EL, et al. Cancer risk after pediatric solid organ transplantation. Pediatrics 2017; 139: e20163893.