title: Effects of statin use on volumetric mammographic density: results from the KARMA study.
abstract: BACKGROUND
  Epidemiological data on statins and breast cancer risk have been inconclusive. The aim of this study was to clarify the role of statins in breast cancer risk by studying their effect on mammographic density.
  
  
  METHODS
  The KARolinska MAmmography project for risk prediction of breast cancer (KARMA) includes 70,877 women who underwent either a screening or clinical mammography from January 2011 to December 2013. In total, 41,102 women responded to a web-based questionnaire, and had raw digital mammograms stored. Volumetric mammographic density was measured using Volpara™ and information on statin use was obtained through linkage with the Swedish National Prescription Register. Analysis of covariance was used to study the effect of statin use on mammographic density, adjusting for a large set of potential confounders. We also studied the effects of statin class and treatment duration and tested for potential effect modification by hormone replacement therapy (HRT).
  
  
  RESULTS
  Statin use was recorded in 3,337 women (8.1 %) of the study population and lipophilic statins was the most commonly prescribed type (93.4 % of all statin users). After multivariable adjustment, percent dense volume was lower in statin users than in non-users (P < 0.001). This association was explained by a larger absolute non-dense volume in statin users (P < 0.001). Overall, no difference in absolute dense volume was detected, but interaction analyses revealed a larger dense volume among statin users who reported ever HRT use (P = 0.03). No differential effects were observed according to statin lipophilicity and treatment duration.
  
  
  CONCLUSIONS
  We observed no overall effect of statin use on mammographic density in terms of absolute dense volume, although a larger absolute dense volume was observed in statin users who reported ever HRT use, which requires further investigation.
authors.affiliation: Division of Oncology and Pathology, Department of Clinical Sciences, Lund University, Skåne University Hospital, SE-221 85, Lund, Sweden. ida.skarping@med.lu.se.
authors.forename: Ida
authors.initials: I
authors.lastname: Skarping
authors.affiliation: Department of Medical Epidemiology and Biostatistics, Karolinska Institute, Stockholm, Sweden. judith.brand@ki.se.
authors.forename: Judith S
authors.initials: JS
authors.lastname: Brand
authors.affiliation: Department of Medical Epidemiology and Biostatistics, Karolinska Institute, Stockholm, Sweden. per.hall@ki.se.
authors.forename: Per
authors.initials: P
authors.lastname: Hall
authors.affiliation: Division of Oncology and Pathology, Department of Clinical Sciences, Lund University, Skåne University Hospital, SE-221 85, Lund, Sweden. signe.borgquist@med.lu.se.|Department of Oncology, Skåne University Hospital, Lund, Sweden. signe.borgquist@med.lu.se.
authors.forename: Signe
authors.initials: S
authors.lastname: Borgquist
mesh_terms: D000328:Adult; D000368:Aged; D000071060:Breast Density; D001943:Breast Neoplasms / Q000139:chemically induced / Q000000981:diagnostic imaging / Q000453:epidemiology* / Q000473:pathology; D005260:Female; D006801:Humans; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors / Q000009:adverse effects*; D042361:Mammary Glands, Human / Q000002:abnormalities* / Q000473:pathology; D008327:Mammography; D008875:Middle Aged; D012307:Risk Factors; D011795:Surveys and Questionnaires
chemical_list: D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors