{"doi":"10.1002/ijc.34917","title":"Metformin and other anti‐diabetic medication use and breast cancer incidence in the <scp>Nurses' Health Studies</scp>","abstract":"We aimed to examine the association between the use of metformin and other anti-diabetic medications and breast cancer incidence within two large prospective cohort studies. We followed 185,181 women who participated in the Nurses' Health Study (NHS; 1994-2016) and the NHSII (1995-2017), with baseline corresponding to the date metformin was approved for type 2 diabetes (T2D) treatment in the US Information on T2D diagnosis, anti-diabetes medications, and other covariates was self-reported at baseline and repeatedly assessed by follow-up questionnaires every 2 years. Breast cancer cases were self-reported and confirmed by medical record review. Hazard ratios (HRs) and 95% confidence intervals (CIs) for the association between medication use and breast cancer were estimated using Cox proportional hazards regression models, adjusting for breast cancer risk factors. During 3,324,881 person-years of follow-up, we ascertained 9,192 incident invasive breast cancer cases, of which 451 were among women with T2D. Compared with women without T2D (n = 169,263), neither metformin use (HR = 0.97; 95% CI = 0.81-1.15) nor other anti-diabetic medications use (HR = 1.11; 95% CI = 0.90-1.36) associated with significantly lower breast cancer incidence. Among women with T2D (n = 15,918), compared with metformin never users, metformin ever use was not significantly inversely associated with breast cancer (HR = 0.92; 95% CI = 0.74-1.15). Although we observed that past use of metformin was inversely associated with breast cancer in the T2D population (HR = 0.67; 95% CI = 0.48-0.94), current use (HR = 1.01; 95% CI = 0.80-1.27) and longer duration of metformin use were not associated with breast cancer (each 2-year interval: HR = 1.01; 95% CI = 0.95-1.07). Overall, metformin use was not associated with the risk of developing breast cancer among the overall cohort population or among women with T2D.","journal":"International Journal of Cancer","year":2024,"id":459334,"datarank":0.0,"base_score":0.0,"endowment":0.0,"self_citation_contribution":0.0,"citation_network_contribution":0.0,"self_endowment_contribution":0.0,"citer_contribution":0.0,"corpus_percentile":null,"corpus_rank":null,"citation_count":4,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":0.6576,"is_data_producer":false,"deposit_databanks":null,"is_oa":true,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":"2024-01-01","fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":434964,"name":"Boyang Chai","orcid":null,"position":1,"is_corresponding":false},{"id":238429,"name":"Wendy Y. Chen","orcid":"0000-0002-6946-1206","position":2,"is_corresponding":false},{"id":337318,"name":"Michelle D. Holmes","orcid":"0000-0002-8664-2172","position":3,"is_corresponding":false},{"id":963433,"name":"Jennifer Erdrich","orcid":"0000-0003-0585-0402","position":4,"is_corresponding":false},{"id":55333,"name":"Frank B. Hu","orcid":"0000-0002-8233-6274","position":5,"is_corresponding":false},{"id":246330,"name":"Bernard Rosner","orcid":"0000-0001-6907-0056","position":6,"is_corresponding":false},{"id":321496,"name":"Rulla M. Tamimi","orcid":"0000-0003-2306-8668","position":7,"is_corresponding":false},{"id":104570,"name":"Walter C. Willett","orcid":"0000-0003-1458-7597","position":8,"is_corresponding":false},{"id":6854,"name":"Jae H. Kang","orcid":"0000-0003-4812-0557","position":9,"is_corresponding":false},{"id":104571,"name":"A. Heather Eliassen","orcid":"0000-0002-3961-6609","position":10,"is_corresponding":false},{"id":519542,"name":"Tengteng Wang","orcid":"0000-0001-9001-186X","position":0,"is_corresponding":true}],"reference_count":51,"raw_metadata":null,"created_at":"2026-07-19T02:03:55.280882Z","pmid":"38520039","pmcid":null,"fwci":null,"citation_percentile":null,"influential_citations":0,"oa_status":null,"license":null,"views":0,"total_file_size_bytes":0,"version_count":0,"fair_f":null,"fair_a":null,"fair_i":null,"fair_r":null,"fair_zscore":null,"fair_rationale":null,"fair_model":null,"fair_agent_version":null,"fair_fulltext_source":null,"fair_has_llm":null,"fair_computed_at":null,"clinical_trials":[],"software_tools":[],"db_accessions":[],"linked_datasets":[],"topics":[]}