In a study of meningioma after growth hormone treatment, the standardized incidence ratio (SIR) associated with prior CNS tumor and GH treatment was 5.3 (95% CI 3.7–7.7) indicating a more than 5-fold increase in risk, whereas the SIR after non-cancer GH treatment was not significantly elevated, suggesting that the main increase in risk arises from the initial treatment for cancer rather than the GH itself [70]. This evidence concerns the gene GH1 and cancer.