title: Calcium channel blockers and risk of breast cancer: a meta-analysis of 17 observational studies.
abstract: OBJECTIVE
  Studies on the association between the use of calcium channel blockers (CCBs) and breast cancer risk have reported inconsistent results. We quantitatively assessed this association by conducting a meta-analysis based on the evidence from observational studies.
  
  
  METHODS
  We searched PubMed, MEDLINE, EMBASE and the Cochrane Library for relevant studies published up to and including December 31, 2013. We calculated pooled risk ratios (RRs) for cancer risk.
  
  
  RESULTS
  A total of 17 studies (9 cohort studies, 8 case-control studies) were selected for further study. These studies included 149,607 female subjects, of which 53,812 were CCBs users, who were followed for 2-16 years. The risks of breast cancer among patients receiving CCBs were significantly different for the pooled RRs (95% confidence interval) of cohort studies 1.08 (0.95, 1.20) and case-control studies 0.98 (0.86, 1.09). Differences were also noted for cancer risk, for CCBs use of <5 years 0.96 (0.78, 1.15), and for >5 years 1.01 (0.74, 1.28), as well as for ever used 1.08 (0.95, 1.20), and for current use 1.13 (0.83, 1.42). The RR for studies longer than 10 years was 1.71 (1.01, 2.42), and for studies evaluating nifedipine was 1.10 (0.87, 1.33) and diltiazem was 0.75 (0.40, 1.10).
  
  
  CONCLUSIONS
  The long-term use of CCBs appears to have a significant relationship with breast cancer. Well-designed clinical trials are needed to optimize the doses and types of these drugs needed to minimize their carcinogenic potential.
authors.affiliation: Oncology Department of Shanghai Municipal Hospital of Traditional Chinese Medicine affiliated to Shanghai TCM University, Shanghai, China.
authors.forename: Wen
authors.initials: W
authors.lastname: Li
authors.affiliation: Oncology Department of Shanghai Municipal Hospital of Traditional Chinese Medicine affiliated to Shanghai TCM University, Shanghai, China.
authors.forename: Qi
authors.initials: Q
authors.lastname: Shi
authors.affiliation: Department of Epidemiology, School of Public Health, Fudan University, Shanghai, China.
authors.forename: Weibing
authors.initials: W
authors.lastname: Wang
authors.affiliation: Oncology Department of Shanghai Municipal Hospital of Traditional Chinese Medicine affiliated to Shanghai TCM University, Shanghai, China.
authors.forename: Jianrong
authors.initials: J
authors.lastname: Liu
authors.affiliation: Oncology Department of Shuguang Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China.
authors.forename: Qi
authors.initials: Q
authors.lastname: Li
authors.affiliation: Oncology Department of Shanghai Municipal Hospital of Traditional Chinese Medicine affiliated to Shanghai TCM University, Shanghai, China.
authors.forename: Fenggang
authors.initials: F
authors.lastname: Hou
mesh_terms: D000328:Adult; D000368:Aged; D000959:Antihypertensive Agents / Q000009:adverse effects*; D001943:Breast Neoplasms / Q000139:chemically induced* / Q000473:pathology; D002121:Calcium Channel Blockers / Q000009:adverse effects*; D016022:Case-Control Studies; D015331:Cohort Studies; D004110:Diltiazem / Q000009:adverse effects*; D005260:Female; D006801:Humans; D006973:Hypertension / Q000188:drug therapy / Q000503:physiopathology; D008875:Middle Aged; D009543:Nifedipine / Q000009:adverse effects*; D016017:Odds Ratio
chemical_list: D000959:Antihypertensive Agents; D002121:Calcium Channel Blockers; D004110:Diltiazem; D009543:Nifedipine