Influence of Inflammation, Insulin Resistance and Excess Body Size on Breast Cancer Risk: A Nested Case-Control Study
AdvisorBrenner, Darren R.
Friedenreich, Christine M.
AuthorHaig, Tiffany R.
Committee MemberLi, Haocheng
high-sensitivity C-reactive protein
Alberta’s Tomorrow Project cohort
nested case-control study
excess body size
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AbstractBackground: Breast cancer is the most common malignancy affecting women in Canada. In 2019, breast cancer represented 25% of all new cancers among Canadian women and 13% of all cancer deaths. Excess body size is associated with postmenopausal breast cancer risk. The mechanisms associating adiposity to breast cancer are unclear. Both inflammation and insulin resistance have been implicated in this association; however, literature to date has been inconsistent. Here, we aim to examine the associations between high-sensitivity C-reactive protein (hsCRP) and hemoglobin A1c (HbA1c), common measures of inflammation and insulin resistance, respectively, with breast cancer risk, while adjusting for measures of excess body size. Methods: We conducted a nested case-control study within the Alberta’s Tomorrow Project cohort (Alberta, Canada) including 197 invasive breast cancer cases and 394 matched controls. Serum concentrations of hsCRP and HbA1c were measured from blood samples collected prior to diagnosis, along with anthropometric measurements, general health, and lifestyle data. Conditional logistic regression was used to evaluate the associations between hsCRP, HbA1c, and breast cancer risk adjusted for body fat percentage and other risk factors for breast cancer. Results: Participants included in this study were a mean age of 65.1 years and mostly postmenopausal (147 cases and 293 controls). More than half were categorized as overweight/obese (60.5% for cases; 64.9% for controls), and median values of hsCRP (0.9; interquartile range (IQR) = 1.8) and HbA1c (5.6; IQR = 0.6) were similar between cases and controls. Higher concentrations of hsCRP were associated with elevated breast cancer risk (odds ratio [OR] = 1.27; 95% confidence interval [CI] = 1.03, 1.55). The observed associations were unchanged with adjustment for body fat percentage. Higher HbA1c concentrations were not significantly associated with an increased risk of incident breast cancer relative to controls (OR = 1.22; 95% CI = 0.17, 8.75). Conclusion: These data suggest that hsCRP, a marker of inflammation, may be associated with elevated breast cancer risk, independent of body fat percentage. However, elevated concentrations of HbA1c did not appear to increase breast cancer risk in this group of women in Alberta.
CitationHaig, T. R. (2020). Influence of Inflammation, Insulin Resistance and Excess Body Size on Breast Cancer Risk: A Nested Case-Control Study (Unpublished master's thesis). University of Calgary, Calgary, AB.
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