Low incidence of second neoplasms among children diagnosed with acute lymphoblastic leukemia after 1983

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Abstract
Second malignant neoplasms are a serious complication after successful treatment of childhood acute lymphoblastic leukemia (ALL). With improvement in survival, it is important to assess the impact of contemporary risk-based therapies on second neoplasms in ALL survivors. A cohort of 8831 children diagnosed with ALL and enrolled on Children's Cancer Group therapeutic protocols between 1983 and 1995 were observed to determine the incidence of second neoplasms and associated risk factors. The median age at diagnosis of ALL was 4.7 years. The cohort had accrued 54 883 person-years of follow-up. Sixty-three patients developed second neoplasms, including solid, nonhematopoietic tumors (n = 39: brain tumors n = 19, other solid tumors n = 20), myeloid leukemia or myelodysplasia (n = 16), and lymphoma (n = 8). The cumulative incidence of any second neoplasm was 1.18% at 10 years (95% confidence interval, 0.8%-1.5%), representing a 7.2-fold increased risk compared with the general population. The risk was increased significantly for acute myeloid leukemia (standardized incidence ratio [SIR] 52.3), non-Hodgkin lymphoma (SIR 8.3), parotid gland tumors (SIR 33.4), thyroid cancer (SIR 13.3), brain tumors (SIR 10.1), and soft tissue sarcoma (SIR 9.1). Multivariate analysis revealed female sex (relative risk [RR] 1.8), radiation to the craniospinal axis (RR 1.6), and relapse of primary disease (RR 3.5) to be independently associated with increased risk of all second neoplasms. Risk of second neoplasms increased with radiation dose (1800 cGy RR 1.5; 2400 cGy RR 3.9). Actuarial survival at 10 years from diagnosis of second neoplasms was 39%. Follow-up of this large cohort that was treated with contemporary risk-based therapy showed that the incidence of second neoplasms remains low after diagnosis of childhood ALL.