title: The interaction of age and hormone replacement therapy on colon adenoma risk.
abstract: BACKGROUND
  Several studies have identified a possible interaction between age and hormone replacement therapy on colon neoplasm risk. We re-evaluated this interaction and determined if this interaction may be explained by the longer duration of estrogen use in older, rather than younger, women.
  
  
  METHODS
  Included in the case-control study were 755 women (169 cases and 586 controls.) who were recruited from patients with no prior history of colorectal neoplasm and undergoing an elective colonoscopy examination.
  
  
  RESULTS
  There was a significant interaction between age and hormone replacement therapy use (P=0.03) with current estrogen users who were over 56 years of age having a reduced odds of colon adenoma (OR, 0.40; 95% CI, 0.16-0.98) when compared to never users. Both older women who had used hormone replacement therapy for 3 or less years (OR, 0.07; 95% CI, 0.006-0.81) and those reporting greater than 10 years of use (OR, 0.27; 95% CI, 0.09-0.80) had a reduced adjusted odds for adenomas when compared to non-users. No apparent association with estrogen replacement therapy was found among younger women (<56 years).
  
  
  CONCLUSIONS
  Duration of use is not likely to explain the stronger association of hormone replacement therapy use with colon neoplasm in older women. Additional work is needed to better characterize the underlying mechanisms associated with this interaction.
authors: Division of General Internal Medicine and Public Health, Vanderbilt University Medical Center, Nashville, TN, USA. Harvey.murff@va.gov
authors: Harvey J
authors: HJ
authors: Murff
authors: Martha J
authors: MJ
authors: Shrubsole
authors: Walter E
authors: WE
authors: Smalley
authors: Huiyun
authors: H
authors: Wu
authors: Yu
authors: Y
authors: Shyr
authors: Reid M
authors: RM
authors: Ness
authors: Wei
authors: W
authors: Zheng
mesh_terms: D000236:Adenoma / Q000188:drug therapy / Q000209:etiology* / Q000473:pathology; D018256:Adenomatous Polyps / Q000473:pathology; D000328:Adult; D000367:Age Factors; D000368:Aged; D016022:Case-Control Studies; D003110:Colonic Neoplasms / Q000188:drug therapy / Q000209:etiology* / Q000473:pathology; D003111:Colonic Polyps / Q000473:pathology; D003113:Colonoscopy; D005260:Female; D020249:Hormone Replacement Therapy; D006801:Humans; D008875:Middle Aged; D017698:Postmenopause; D012307:Risk Factors; D013997:Time Factors