LOW-INTENSITY, non-myeloablative conditioning regimens have been linked to a greater risk of secondary neoplasms, including myelodysplastic syndrome (MDS) and leukaemia, in patients with sickle cell disease (SCD) treated with a haematopoietic stem cell transplant (HSCT). While the treatment can cure children with SCD, it leads to an increased risk for substantial morbidities such as secondary neoplasms and death. A research team analysed the risk factors and incidence of secondary neoplasms after HSCT in patients with SCD.
The study included data from 1,096 patients who had an HSCT between 1991–2016. Of these, 22 patients developed a secondary neoplasm and 1,074 did not. In total, 51% of patients were male and the median age was 15 years. Secondary neoplasms were found in 45% of patients, while none were found in 11% of patients, whose donor was a haploidentical relative. Of the transplants, 16% of cases without secondary neoplasm and 64% of other cases had peripheral blood as the stem cell source, while 71% and 27% received bone marrow, respectively.
Ten-year incidence for secondary neoplasms was 2.4%, including 0.7% for solid tumours and 1.7% for leukaemia or myelodysplastic syndrome. The median time to diagnosis for these was 40 months. Compared to myeloablative regimens, low-intensity, non-myeloablative conditioning regimens were significantly associated with a higher risk of developing secondary neoplasms (hazard ratio: 7.78; 95% confidence interval: 2.20–27.53; p=0.0015) and leukaemia or MDS (hazard ratio: 22.69; 95% confidence interval: 4.34–118.66; p=0.0002).
The team concluded that the higher risk for leukaemia or MDS might in part be mitigated by the choice of conditioning regimens that are likely to result in full-donor chimerism.