Treatment-related myelodysplasia and acute leukemia in non-Hodgkin's lymphoma patients

Purpose: Standard therapies for non-Hodgkin's lymphoma (NHL) are associated with an increased risk of developing treatment-related myelodysplastic syndrome or acute myelogenous leukemia (tMDS/AML). However, there is considerable debate over the incidence or risk of tMDS/ AML in NHL patients treated with any particular modality and the factors that contribute to malignant transformation. Design: Conclusions were based on thorough analysis of data reported in the peer-reviewed literature and careful examination of the statistical methodology and methods for identifying cases of tMDS/AML. Unless noted, data are reported only for NHL patients, excluding Hodgkin's disease patients. Results: Despite differences in methods used to identify cases and to estimate the cumulative incidence over time (actuarial v cumulative calculations), up to 10% of NHL patients treated with either conventional-dose chemotherapy or high-dose therapy and autologous stem-cell transplantation may develop tMDS/AML within 10 years of primary therapy. Kaplan-Meier estimates of the actuarial incidence, which are based on censoring of patients who died without developing tMDS/AML, can lead to artificially high estimates with large confidence intervals at later time points. Although there is much debate about the cause(s) of tMDS/AML, there is compelling evidence that alkylating agents, certain other leukemogenic agents, and total-body irradiation (TBI) cause chromosomal damage that can lead to tMDS/AML. Conclusion: Limiting exposure to alkylating agents and eliminating TBI from transplantation conditioning regimens may reduce the relative risk of tMDS/AML.