title: Metformin and the incidence of viral associated cancers in patients with type 2 diabetes.
abstract: Limited studies have associated metformin with a reduced risk of viral associated cancers, however these had a number of methodological shortcomings. This study investigated whether the use of metformin is associated with a reduced risk of viral associated cancers in patients with type 2 diabetes. A cohort of 137,754 patients newly-prescribed non-insulin antidiabetic drugs between January 1, 1988 and March 31, 2016 was identified from the UK Clinical Practice Research Datalink and followed until a first-ever diagnosis of a viral associated cancer, death from any cause, end of registration with the practice, or March 31, 2016. Time-varying use of metformin was compared with use of other antidiabetic drugs, with exposures lagged by one year for latency purposes. Time-dependent Cox proportional hazards models were used to estimate adjusted hazard ratios (HRs) with 95% confidence intervals (CIs) of incident viral associated cancer with use of metformin overall, by cumulative duration of use and viral etiology. Overall, there were 424 viral associated cancers during 759,810 person-years of follow-up (crude rate of 5.6 per 10,000 person-years). Metformin was not associated with a decreased rate of viral associated cancer (HR: 0.93, 95% CI: 0.65-1.32). There was no evidence of a duration-response relationship in terms of cumulative duration of use (p trend = 0.69), including with use of metformin for more than 10 years (HR 1.02, 95% CI: 0.52-1.99), or by viral etiology. In this large population-based cohort study, the use of metformin was not associated with a reduced risk of viral associated cancer.
authors.affiliation: Centre for Clinical Epidemiology, Lady Davis Institute, Jewish General Hospital, Quebec, Canada, Montréal.|Department of Epidemiology, Biostatistics and Occupational Health, McGill University, Montréal, Quebec, Canada.
authors.forename: Blánaid M
authors.initials: BM
authors.lastname: Hicks
authors.affiliation: Centre for Clinical Epidemiology, Lady Davis Institute, Jewish General Hospital, Quebec, Canada, Montréal.
authors.forename: Hui
authors.initials: H
authors.lastname: Yin
authors.affiliation: Centre for Clinical Epidemiology, Lady Davis Institute, Jewish General Hospital, Quebec, Canada, Montréal.
authors.forename: Liliya
authors.initials: L
authors.lastname: Sinyavskaya
authors.affiliation: Centre for Clinical Epidemiology, Lady Davis Institute, Jewish General Hospital, Quebec, Canada, Montréal.|Department of Epidemiology, Biostatistics and Occupational Health, McGill University, Montréal, Quebec, Canada.
authors.forename: Samy
authors.initials: S
authors.lastname: Suissa
authors.affiliation: Centre for Clinical Epidemiology, Lady Davis Institute, Jewish General Hospital, Quebec, Canada, Montréal.|Department of Epidemiology, Biostatistics and Occupational Health, McGill University, Montréal, Quebec, Canada.|Gerald Bronfman Department of Oncology, McGill University, Montréal, Quebec, Canada.
authors.forename: Laurent
authors.initials: L
authors.lastname: Azoulay
authors.affiliation: Centre for Clinical Epidemiology, Lady Davis Institute, Jewish General Hospital, Quebec, Canada, Montréal.|Department of Epidemiology, Biostatistics and Occupational Health, McGill University, Montréal, Quebec, Canada.|Department of Medicine, McGill University, Montreal, Quebec, Canada.
authors.forename: Paul
authors.identifier: 0000-0001-7485-2546
authors.initials: P
authors.lastname: Brassard
mesh_terms: D000368:Aged; D015331:Cohort Studies; D003924:Diabetes Mellitus, Type 2 / Q000188:drug therapy* / Q000453:epidemiology / Q000473:pathology / Q000821:virology; D005260:Female; D006801:Humans; D007004:Hypoglycemic Agents / Q000627:therapeutic use*; D008297:Male; D008687:Metformin / Q000627:therapeutic use*; D008875:Middle Aged; D009369:Neoplasms / Q000188:drug therapy* / Q000453:epidemiology / Q000473:pathology / Q000821:virology; D016016:Proportional Hazards Models; D012307:Risk Factors
chemical_list: D007004:Hypoglycemic Agents; D008687:Metformin
keywords: metformin; pharmacoepidemiology; type 2 diabetes; viral neoplasm