title: Flax and Breast Cancer: A Systematic Review.
abstract: BACKGROUND
  Flax is a food and dietary supplement commonly used for menopausal symptoms. Flax is known for its lignan, α-linolenic acid, and fiber content, components that may possess phytogestrogenic, anti-inflammatory, and hormone modulating effects, respectively. We conducted a systematic review of flax for efficacy in improving menopausal symptoms in women living with breast cancer and for potential impact on risk of breast cancer incidence or recurrence.
  
  
  METHODS
  We searched MEDLINE, Embase, the Cochrane Library, and AMED from inception to January 2013 for human interventional or observational data pertaining to flax and breast cancer.
  
  
  RESULTS
  Of 1892 records, we included a total of 10 studies: 2 randomized controlled trials, 2 uncontrolled trials, 1 biomarker study, and 5 observational studies. Nonsignificant (NS) decreases in hot flash symptomatology were seen with flax ingestion (7.5 g/d). Flax (25 g/d) increased tumor apoptotic index (P< .05) and decreased HER2 expression (P< .05) and cell proliferation (Ki-67 index; NS) among newly diagnosed breast cancer patients when compared with placebo. Uncontrolled and biomarker studies suggest beneficial effects on hot flashes, cell proliferation, atypical cytomorphology, and mammographic density, as well as possible anti-angiogenic activity at doses of 25 g ground flax or 50 mg secoisolariciresinol diglycoside daily. Observational data suggests associations between flax and decreased risk of primary breast cancer (adjusted odds ratio [AOR] = 0.82; 95% confidence interval [CI] = 0.69-0.97), better mental health (AOR = 1.76; 95% CI = 1.05-2.94), and lower mortality (multivariate hazard ratio = 0.69; 95% CI = 0.50-0.95) among breast cancer patients.
  
  
  CONCLUSIONS
  Current evidence suggests that flax may be associated with decreased risk of breast cancer. Flax demonstrates antiproliferative effects in breast tissue of women at risk of breast cancer and may protect against primary breast cancer. Mortality risk may also be reduced among those living with breast cancer.
authors.affiliation: Canadian College of Naturopathic Medicine, Toronto, Ontario, Canada Ottawa Integrative Cancer Center, Ottawa, Ontario, Canada.
authors.forename: Gillian
authors.initials: G
authors.lastname: Flower
authors.affiliation: Canadian College of Naturopathic Medicine, Toronto, Ontario, Canada.
authors.forename: Heidi
authors.initials: H
authors.lastname: Fritz
authors.affiliation: University of British Columbia School of Nursing, Vancouver, British Columbia, Canada CAMEO Program, Vancouver, British Columbia, Canada.
authors.forename: Lynda G
authors.initials: LG
authors.lastname: Balneaves
authors.affiliation: Ottawa Hospital Research Institute, Ottawa, Ontario, Canada Ottawa Regional Cancer Centre, Ottawa Hospital, Ontario, Canada.
authors.forename: Shailendra
authors.initials: S
authors.lastname: Verma
authors.affiliation: Canadian College of Naturopathic Medicine, Toronto, Ontario, Canada.
authors.forename: Becky
authors.initials: B
authors.lastname: Skidmore
authors.affiliation: Canadian College of Naturopathic Medicine, Toronto, Ontario, Canada The University of Toronto, Toronto, Ontario, Canada.
authors.forename: Rochelle
authors.initials: R
authors.lastname: Fernandes
authors.affiliation: Canadian College of Naturopathic Medicine, Toronto, Ontario, Canada The University of Toronto, Toronto, Ontario, Canada.
authors.forename: Deborah
authors.initials: D
authors.lastname: Kennedy
authors.affiliation: Canadian College of Naturopathic Medicine, Toronto, Ontario, Canada The University of Toronto, Toronto, Ontario, Canada.
authors.forename: Kieran
authors.initials: K
authors.lastname: Cooley
authors.affiliation: McMaster University, Hamilton, Ontario, Canada.
authors.forename: Raimond
authors.initials: R
authors.lastname: Wong
authors.affiliation: McMaster University, Hamilton, Ontario, Canada.
authors.forename: Stephen
authors.initials: S
authors.lastname: Sagar
authors.affiliation: Ottawa Hospital Research Institute, Ottawa, Ontario, Canada.
authors.forename: Dean
authors.initials: D
authors.lastname: Fergusson
authors.affiliation: Canadian College of Naturopathic Medicine, Toronto, Ontario, Canada Ottawa Integrative Cancer Center, Ottawa, Ontario, Canada Ottawa Hospital Research Institute, Ottawa, Ontario, Canada dseely@ccnm.edu.
authors.forename: Dugald
authors.initials: D
authors.lastname: Seely
mesh_terms: D000071060:Breast Density / Q000188:drug therapy; D001943:Breast Neoplasms / Q000473:pathology / Q000517:prevention & control*; D002072:Butylene Glycols / Q000008:administration & dosage / Q000494:pharmacology; D049109:Cell Proliferation / Q000187:drug effects; D019587:Dietary Supplements; D005260:Female; D019597:Flax / Q000737:chemistry*; D005960:Glucosides / Q000008:administration & dosage / Q000494:pharmacology; D019584:Hot Flashes / Q000188:drug therapy / Q000209:etiology; D006801:Humans; D008593:Menopause
chemical_list: D002072:Butylene Glycols; D005960:Glucosides; C090142:secoisolariciresinol diglucoside
keywords: Linum usitatissimum; breast cancer; breast neoplasm; complementary and alternative medicine (CAM); flax; hot flashes; integrative oncology; menopause; phytoestrogen; systematic review