Cancer risk in children and young adults born preterm: A systematic review and meta-analysis

Introduction Risk of developing a malignancy when born premature is unknown. We hypothesised that risk of certain cancers might be increased in youth born preterm versus term. We therefore performed a systematic review and meta-analysis to evaluate the incidence of malignancy in the context of preterm birth, according to various cancer types. Methods The study was designed per MOOSE and PRISMA guidelines. Articles were identified through November 2015. Observational studies exploring the association between childhood malignancy and birth characteristics were included. Of the 1658 records identified, 109 full text articles were evaluated for eligibility. Random effects meta-analyses were conducted on 10/26 studies retained; 95% confidence intervals were computed and adjusted following sensitivity analysis. Publication bias was evaluated using funnel plots, Begg's and Egger's tests. Results No differences in risk of primary central nervous system tumor [OR 1.05; 95% CI 0.93-1.17, 5 studies, 580 cases] and neuroblastoma [OR 1.09; 95% CI 0.90-1.32, 5 studies, 211 cases] were observed in individuals born <37 versus >= 37 weeks' gestation. Preterm birth was consistently associated with hepatoblastoma [ORs 3.12 (95% CI 2.32-4.20), 1.52 (95% CI 1.1-2.1), 1.82 (95% CI 1.01-3.26), and 2.65 (95% CI 1.98-3.55)], but not leukemia, astrocytoma, ependymoma, medulloblastoma, lymphoma, nephroblastoma, rhabdomyosarcoma, retinoblastoma or thyroid cancer. Conclusions Children born premature may be at increased risk for hepatoblastoma but there is no strong evidence of an increased risk of primary central nervous system tumours or neuroblastoma. There is insufficient evidence to conclude whether prematurity modulates the risk of other childhood cancers.