title: Antihypertensive agents and the risk of breast cancer in women aged 55 years and older: a nested case-control study.
abstract: OBJECTIVE
  The study aimed to investigate the association of long-term use of different antihypertensive agents with incident breast cancer.
  
  
  METHODS
  A total of 794 ,533 women aged at least 55 years were identified from Taiwan National Health Insurance claims database during 2001-2011. As of 31 December 2011, incident breast cancer patients were included as cases, and 1 : 4 age-matched controls were selected by risk-set sampling scheme. Logistic regression models were applied to estimate the odds ratios (ORs) and 95% confidence intervals (CIs) of breast cancer incidence associated with different durations of use of angiotensin-converting enzyme inhibitors/angiotensin receptor blockers, β-blockers, and dihydropyridine calcium channel blockers (DHP CCBs). Different restriction rules were applied to reveal the potential effects of confounding by indication.
  
  
  RESULTS
  Among the 9397 incident breast cancer patients and 37 ,588 controls, a significantly elevated risk was found for relatively short-term use of DHP CCBs (<6 years) but not in those observed for more than 6 years. There was no association between either angiotensin-converting enzyme inhibitors/angiotensin receptor blockers or β-blockers use and breast cancer. Although restricting our analyses to those with any prescription of antihypertensive medications in 2001 or those with diagnosis of hypertension, there was no longer a statistically significant association between any use of DHP CCBs and breast cancer (OR: 1.21, 95% CI: 0.88-1.67 for the former, and OR: 1.71, 95% CI: 0.99-2.95 for the latter).
  
  
  CONCLUSIONS
  The results demonstrated the potential effect of confounding by indication, and thus, did not suggest any association of the use of antihypertensive medication and breast cancer risk.
authors.affiliation: aDepartment of Internal Medicine, National Taiwan University Hospital and College of Medicine bInstitute of Preventive Medicine, College of Public Health, National Taiwan University cDepartment of Family Medicine, National Taiwan University Hospital and College of Medicine, Taipei dDepartment of Community and Family Medicine eCardiovascular Center, National Taiwan University Hospital Yun-Lin Branch, Yun-Lin, Taiwan.
authors.forename: Chia-Hsuin
authors.initials: CH
authors.lastname: Chang
authors.forename: Chien-Hsieh
authors.initials: CH
authors.lastname: Chiang
authors.forename: Chung-Jen
authors.initials: CJ
authors.lastname: Yen
authors.forename: Li-Chiu
authors.initials: LC
authors.lastname: Wu
authors.forename: Jou-Wei
authors.initials: JW
authors.lastname: Lin
authors.forename: Mei-Shu
authors.initials: MS
authors.lastname: Lai
mesh_terms: D000319:Adrenergic beta-Antagonists / Q000627:therapeutic use*; D000368:Aged; D057911:Angiotensin Receptor Antagonists / Q000627:therapeutic use*; D000806:Angiotensin-Converting Enzyme Inhibitors / Q000627:therapeutic use*; D000959:Antihypertensive Agents / Q000627:therapeutic use*; D001943:Breast Neoplasms / Q000453:epidemiology*; D002121:Calcium Channel Blockers / Q000627:therapeutic use*; D016022:Case-Control Studies; D004095:Dihydropyridines / Q000627:therapeutic use; D005260:Female; D006801:Humans; D006973:Hypertension / Q000188:drug therapy* / Q000453:epidemiology; D015994:Incidence; D016015:Logistic Models; D008875:Middle Aged; D016017:Odds Ratio; D012307:Risk Factors; D013624:Taiwan / Q000453:epidemiology
chemical_list: D000319:Adrenergic beta-Antagonists; D057911:Angiotensin Receptor Antagonists; D000806:Angiotensin-Converting Enzyme Inhibitors; D000959:Antihypertensive Agents; D002121:Calcium Channel Blockers; D004095:Dihydropyridines