Supplementary Material for: Assessment of Primary Cancer Incidence in Growth Hormone-Treated Children: Comparison of a Multinational Prospective Observational Study with Population Databases

Background/Aims: Although results of the majority of clinical studies have shown no association between growth hormone (GH) treatment in childhood and risk of primary cancer, concerns remain regarding the potential influence of GH therapy on neoplastic cell growth. This study evaluated the incidence of primary malignancies in a large observational study of paediatric GH treatment. Methods: Primary cancer incidence was assessed in a cohort of 19,054 GH-treated children without a reported prestudy history of malignancy in the observational Genetics and Neuroendocrinology of Short Stature International Study (GeNeSIS). The standardised incidence ratio (SIR) for primary cancer in GH-treated children was determined by comparing cancer incidence in the GeNeSIS study population with incidence rates for country-, age-, and sex-matched cohorts of the general population. Results: During a mean follow-up of 3.4 years in GeNeSIS (64,705 person-years), 13 incident potential primary cancers were identified in GH-treated patients. The SIR (95% confidence interval) for all observed cancers was 1.02 (0.54-1.75), and the crude incidence was 20.1 (10.7-34.4) cases per 100,000 person-years. Conclusion: Acknowledging the relatively short follow-up in our study, GH-treated children without a history of previous malignancy did not have a higher risk of all-site primary cancer during the study when compared to general-population cancer registries.