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dc.contributor.authorBoren, David
dc.contributor.otherQueen's University (Kingston, Ont.). Theses (Queen's University (Kingston, Ont.))en
dc.date.accessioned2017-09-26T18:50:43Z
dc.date.available2017-09-26T18:50:43Z
dc.identifier.urihttp://hdl.handle.net/1974/22753
dc.description.abstractBackground: Breast density and insulin-like growth factor-I (IGF-I) have both been linked to breast cancer risk. Prior research has shown an overwhelmingly positive association between these two factors, but almost exclusively in pre-menopausal women. In fact, few studies have focused on this relationship in post-menopausal women. Evidence suggests that reproductive hormones, like estrogen, might play a role in the overarching pathways connecting IGF-I, breast density, and breast cancer. Objective: The objectives of this thesis were to examine the relationship between IGF-I and breast density in post-menopausal women, and then determine if there was any effect modification of this association by estrogen level. Methods: This thesis focused on a cohort of 568 post-menopausal women from a clinical trial that analyzed the efficacy of exemestane in reducing breast cancer risk. Cumulus software was used to calculate percent breast density values from provided mammograms. These values were then dichotomized as being either low (< 25%) or moderately high (≥ 25%). IGF-I concentrations were determined by ELISA from collected serum samples, and then standardized prior to data analysis. The association between IGF-I level (standardized) and percent breast density (dichotomized) was analyzed using multivariable modified Poisson regression. In addition, log-transformed percent breast density values were used to measure the association through multiple linear regression. Effect modification by treatment arm (i.e. exemestane or placebo) was examined to determine if estrogen level plays any part in this relationship. Results: Percent breast density values were lower than anticipated (μ = 5.54%) with few women (13.9%) being classified as having moderately high breast density. Serum IGF-I levels were higher than expected (μ = 178.52 ng/mL), due in large part to exemestane administration. After identifying and controlling for potential covariates, there was no significant association detected between IGF-I and percent breast density in either its dichotomized (p = 0.30) or log-transformed (p = 0.60) form. The inclusion of an interaction term also returned a non-significant result for effect modification of these relationships by estrogen level. Conclusion: There was no observed association between IGF-I and breast density in postmenopausal women. This was seen regardless of estrogen level, as determined by treatment arm.en_US
dc.language.isoenen_US
dc.relation.ispartofseriesCanadian thesesen
dc.rightsQueen's University's Thesis/Dissertation Non-Exclusive License for Deposit to QSpace and Library and Archives Canadaen
dc.rightsProQuest PhD and Master's Theses International Dissemination Agreementen
dc.rightsIntellectual Property Guidelines at Queen's Universityen
dc.rightsCopying and Preserving Your Thesisen
dc.rightsThis publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner.en
dc.subjectInsulin-Like Growth Factor-Ien_US
dc.subjectBreast Densityen_US
dc.subjectPost-Menopausalen_US
dc.titleExamining the Relationship Between Insulin-Like Growth Factor-I and Breast Density in Post-Menopausal Womenen_US
dc.typeThesisen
dc.description.degreeMaster of Scienceen_US
dc.contributor.supervisorRichardson, Harriet
dc.contributor.departmentPublic Health Sciencesen_US
dc.embargo.termsI am requesting a maximum restriction of 5 years in order to allow time for manuscript publication based on thesis findings .en_US
dc.embargo.liftdate2022-09-25T21:15:08Z


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