Second neoplasms in survivors of childhood acute lymphoblastic leukemia treated with both chemotherapy and radiotherapy.

Abstract

e293 Background: Second malignant neoplasms (SMNs) are a concern in survivors of childhood cancer. Chemotherapy forms the mainstay of treatment for acute lymphoblastic leukaemia, but radiotherapy is used in certain situations. As both chemotherapy and radiotherapy can be carcinogenic, patients treated with both modalities may be at a higher risk of SMNs. This study aims to investigate the incidence of SMNs in patients treated with both chemotherapy and radiotherapy. Methods: Children aged 16 years and below diagnosed with acute lymphoblastic leukaemia from 1993 to 2014 were identified in the Childhood Cancer Registry. Manual and electronic medical records were reviewed for information on demographics, management and SMNs. Results: A total of 64 patients treated with both chemotherapy and radiotherapy were identified. Seventeen (26.6%) were female and 47 (73.4%) were male. The median follow-up was 9.2 years (range, 1.1-22.0 years). The median age at diagnosis was 5.3 years, (range, 0.3-14.6 years). The median age at which radiotherapy was given was 6.6 years (range, 2.9-15.4 years). SMNs were noted in 3 of 64 (4.7%) patients. Two of 3 patients had a SMN within the radiation field (both cranial). The histological diagnoses were basal cell carcinoma and cerebral PNET. The remaining patient had an ovarian immature teratoma outside the radiation field. The latency period ranged from 8.3 years to 13.3 years (median 9.4 years) from date of diagnosis to development of SMN. The estimated 10-year cumulative incidence was 4.3%, 95% CI [0.01, 0.13] using a competing risks analysis. Radiotherapy data was available in 63 patients. Fifty-one of 63 (81.0%) received cranial irradiation, of which 3 (5.9%) also received spinal irradiation. Total body irradiation was performed in 20 of 63 (31.7%), and testicular irradiation in 17 of 63 (27.0%) patients. The orbit was targeted in 3 of 63 (4.8%) patients. Conclusions: Long term survivors of acute lymphoblastic leukaemia treated with both chemotherapy and radiotherapy may have a significant risk of second malignant neoplasms, which may occur years after the initial diagnosis.