Late thyroid complications in survivors of childhood acute leukemia. An LEA study

Thyroid complications are known side effects of irradiation. However, ă the risk of such complications in childhood acute leukemia survivors who ă received either central nervous system irradiation or hematopoietic stem ă cell transplantation is less described. We prospectively evaluated the ă incidence and risk factors for thyroid dysfunction and tumors in ă survivors of childhood acute myeloid or lymphoid leukemia. A total of ă 588 patients were evaluated for thyroid function, and 502 individuals ă were assessed for thyroid tumors (median follow-up duration: 12.6 and ă 12.5 years, respectively). The cumulative incidence of hypothyroidism ă was 17.3% (95% CI: 14.1-21.1) and 24.6% (95% CI: 20.4-29.6) at 10 ă and 20 years from leukemia diagnosis, respectively. Patients who ă received total body irradiation (with or without prior central nervous ă system irradiation) were at higher risk of hypothyroidism (adjusted HR: ă 2.87; P=0.04 and 2.79, P=0.01, respectively) as compared with ă transplanted patients who never received any irradiation. Patients ă transplanted without total body irradiation who received central nervous ă system irradiation were also at higher risk (adjusted HR: 3.39; P=0.02). ă Patients irradiated or transplanted at older than 10 years of age had a ă lower risk (adjusted HR: 0.61; P=0.02). Thyroid malignancy was found in ă 26 patients (5.2%). Among them, two patients had never received any ă type of irradiation: alkylating agents could also promote thyroid ă cancer. The cumulative incidence of thyroid malignancy was 9.6% (95% ă CI: 6.0-15.0) at 20 years. Women were at higher risk than men (adjusted ă HR: 4.74; P=0.002). In conclusion, thyroid complications are frequent ă among patients who undergo transplantation after total body irradiation ă and those who received prior central nervous system irradiation. Close ă monitoring is thus warranted for these patients.