biostudies-literatureGetu MAShenzhen Key Medical Discipline Construction Fund & Sanming Project of Medicine in ShenzhenShenzhen Key Medical Discipline Construction Fund & Sanming Project of Medicine in ShenzhenNational Natural Science Foundation of ChinaMedicine-Engineering Interdisciplinary Research Foundation of Shenzhen UniversityShenzhen Science and Technology Program11371https://www.ebi.ac.uk/biostudies/studies/S-EPMC11965372biostudies-literatureUnknown15(1)Previous observational studies have suggested a potential link between Type 1 Diabetes (T1D) and site-specific cancer risk. However, the nature of this association remains uncertain due to confounding factors, reverse causation, and biases inherent in observational research. To address this gap, we conducted a two-sample Mendelian randomization (MR) study to assess the causal relationship between T1D and 22 site-specific cancers. Using summary statistics from large-scale genome-wide association studies of European ancestry, comprising data on T1D (N = 520,580) and the 22 site-specific cancers, we selected single nucleotide polymorphisms strongly associated with T1D as instruments for our analysis. Causal relationships were primarily evaluated through inverse-variance weighting-based analysScientific reportsA two-sample Mendelian randomization study of type 1 diabetes and the risk of 22 site-specific cancers.PMC11965372GJHZ202209131430050102023YG019SZSM20211100282104596Gong PZhang XYing YGetu MAfalseA two-sample Mendelian randomization study of type 1 diabetes and the risk of 22 site-specific cancers.Previous observational studies have suggested a potential link between Type 1 Diabetes (T1D) and site-specific cancer risk. However, the nature of this association remains uncertain due to confounding factors, reverse causation, and biases inherent in observational research. To address this gap, we conducted a two-sample Mendelian randomization (MR) study to assess the causal relationship between T1D and 22 site-specific cancers. Using summary statistics from large-scale genome-wide association studies of European ancestry, comprising data on T1D (N = 520,580) and the 22 site-specific cancers, we selected single nucleotide polymorphisms strongly associated with T1D as instruments for our analysis. Causal relationships were primarily evaluated through inverse-variance weighting-based analys2025-01-01T00:00:00Z2025 Apr2025-06-28T03:05:21.681Z2025-06-28T03:05:21.681ZS-EPMC119653724017544510.1038/s41598-025-89288-3