Characteristics and Outcomes of Second Malignant Neoplasms after Childhood Cancer Treatment: Multi-Center Retrospective Survey.

This retrospective study investigated the clinical characteristics and outcomes of second malignant neoplasms (SMNs) in survivors of childhood cancer from multiple institutions in Korea. A total of 102 patients from 11 institutions who developed SMN after childhood cancer treatment between 1998 and 2011 were retrospectively enrolled. The most common primary malignant neoplasms (PMNs) were central nervous system (CNS) tumors (n = 17), followed by acute lymphoblastic leukemia (n = 16), non-Hodgkin lymphoma (n = 13), and osteosarcoma (n = 12). The most common SMNs were therapy-related myeloid neoplasms (t-MNs; acute myeloid leukemia [AML], 29 cases; myelodysplastic syndrome [MDS], 12 cases), followed by thyroid carcinomas (n = 15) and CNS tumors (n = 10). The median latency period was 4.9 years (range, 0.5-18.5 years). Among 45 patients with solid tumors defined as an SMN, 15 (33%) developed the lesion in a field previously subjected to radiation. The 5-year overall survival (OS) rate of patients with an SMN was 45% with a median follow-up time of 8.6 years. Patients with AML, MDS, and CNS tumors exhibited the poorest outcomes with 5-year OS rates of 18%, 33%, and 32%, respectively, whereas those with second osteosarcoma showed comparable outcomes (64%) to patients with primary counterpart and those with second thyroid carcinoma had a 100% OS rate. Further therapeutic efforts are recommended to improve the survival outcomes in patients with SMNs, especially in cases with t-MNs and CNS tumors.