title: Potential increased risk of cancer from commonly used medications: an umbrella review of meta-analyses.
abstract: Several commonly used medications have been associated with increased cancer risk in the literature. Here, we evaluated the strength and consistency of these claims in published meta-analyses. We carried out an umbrella review of 74 meta-analysis articles addressing the association of commonly used medications (antidiabetics, antihyperlipidemics, antihypertensives, antirheumatics, drugs for osteoporosis, and others) with cancer risk where at least one meta-analysis in the medication class included some data from randomized trials. Overall, 51 articles found no statistically significant differences, 13 found some decreased cancer risk, and 11 found some increased risk (one reported both increased and decreased risks). The 11 meta-analyses that found some increased risks reported 16 increased risk estimates, of which 5 pertained to overall cancer and 11 to site-specific cancer. Six of the 16 estimates were derived from randomized trials and 10 from observational data. Estimates of increased risk were strongly inversely correlated with the amount of evidence (number of cancer cases) (Spearman's correlation coefficient = -0.77, P < 0.001). In 4 of the 16 topics, another meta-analysis existed that was larger (n = 2) or included better controlled data (n = 2) and in all 4 cases there was no statistically significantly increased risk of malignancy. No medication or class had substantial and consistent evidence for increased risk of malignancy. However, for most medications we cannot exclude small risks or risks in population subsets. Such risks are unlikely to be possible to document robustly unless very large, collaborative studies with standardized analyses and no selective reporting are carried out.
authors: Stanford Prevention Research Center, Department of Medicine and Department of Health Research and Policy, Stanford University School of Medicine, Stanford.
authors: J P A
authors: JP
authors: Ioannidis
authors: Y
authors: Y
authors: Zhou
authors: C Q
authors: CQ
authors: Chang
authors: S D
authors: SD
authors: Schully
authors: M J
authors: MJ
authors: Khoury
authors: A N
authors: AN
authors: Freedman
mesh_terms: D000959:Antihypertensive Agents / Q000009:adverse effects; D018501:Antirheumatic Agents / Q000009:adverse effects; D050071:Bone Density Conservation Agents / Q000009:adverse effects; D006801:Humans; D007004:Hypoglycemic Agents / Q000009:adverse effects; D000960:Hypolipidemic Agents / Q000009:adverse effects; D015201:Meta-Analysis as Topic; D009369:Neoplasms / Q000139:chemically induced*; D064887:Observational Studies as Topic; D016032:Randomized Controlled Trials as Topic; D012306:Risk
chemical_list: D000959:Antihypertensive Agents; D018501:Antirheumatic Agents; D050071:Bone Density Conservation Agents; D007004:Hypoglycemic Agents; D000960:Hypolipidemic Agents
keywords: cancer; meta-analysis; pharmacoepidemiology; randomized trials; review