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Background: A high body mass index (BMI, kg/m 2 ) is associated with decreased risk of breast cancer before menopause, but increased risk after menopause. Exactly when this reversal occurs in relation to menopause is unclear. Locating that change point could provide insight into the role of adiposity in breast cancer etiology., Methods: We examined the association between BMI and breast cancer risk in the Premenopausal Breast Cancer Collaborative Group, from age 45 up to breast cancer diagnosis, loss to follow-up, death, or age 55, whichever came first. Analyses included 609,880 women in 16 prospective studies, including 9956 who developed breast cancer before age 55. We fitted three BMI hazard ratio (HR) models over age-time: constant, linear, or nonlinear (via splines), applying piecewise exponential additive mixed models, with age as the primary time scale. We divided person-time into four strata: premenopause; postmenopause due to natural menopause; postmenopause because of interventional loss of ovarian function (bilateral oophorectomy (BO) or chemotherapy); postmenopause due to hysterectomy without BO. Sensitivity analyses included stratifying by BMI in young adulthood, or excluding women using menopausal hormone therapy., Results: The constant BMI HR model provided the best fit for all four menopausal status groups. Under this model, the estimated association between a five-unit increment in BMI and breast cancer risk was HR=0.87 (95% CI: 0.85, 0.89) before menopause, HR=1.00 (95% CI: 0.96, 1.04) after natural menopause, HR=0.99 (95% CI: 0.93, 1.05) after interventional loss of ovarian function, and HR=0.88 (95% CI: 0.76, 1.02) after hysterectomy without BO., Conclusion: The BMI breast cancer HRs remained less than or near one during the 45-55 year age range indicating that the transition to a positive association between BMI and risk occurs after age 55., Competing Interests: Declaration of Competing Interest none., (Published by Elsevier Ltd.)

Background: Healthy dietary patterns characterized by high intake of fruits and vegetables, grains/cereals, and lean meat/fish, and low intake of red/processed meats and refined carbohydrates, have been shown to be associated with reduced risk of colorectal cancer, but evidence regarding their association with colorectal cancer subsites is limited. Hence, this study was conducted to assess the association of a healthy dietary pattern, as reflected in the Healthy Eating Index (HEI) (a composite score based on consumption of various food groups), with risk of colorectal cancer, overall and by subsite., Methods: We conducted a case-cohort study in the Canadian Study of Diet, Lifestyle and Health (CSDLH). The study included all cases of incident colorectal cancer in the entire cohort, and an age-stratified subcohort of 3185 women and 2622 men. Cox regression models were used to estimate hazard ratios (HR) for the association between the HEI and the risk of colorectal cancer, overall and by subsite. We also assessed the association by sex and by selected metabolic factors., Results: For both sexes combined, the highest quintile of the HEI score was inversely associated with risk of colorectal cancer, colon cancer and proximal colon cancer (HR: 0.65; 95% CI: 0. 49-0.85, HR: 0.60, 95% CI: 0.44-0.83 and HR: 0.54, 95% CI: 0.35-0.85, respectively). However, these associations were mostly observed among men (HR: 0.56; 95% CI: 0.38-0.81, HR: 0.44, 95% CI: 0.28-0.69 and HR: 0.26; 95% CI: 0.12-0.56, for colorectal cancer, colon cancer and proximal colon cancer, respectively; p-interactions=0.029, 0.032 and 0.063, respectively). An inverse association was also observed between the HEI and risk of colorectal cancer among normal weight participants, overweight/obese participants, non-smokers, non-alcohol drinkers and participants who were physically inactive., Conclusion: A healthy dietary pattern may reduce risk of colorectal cancer, particularly among men., Competing Interests: Declaration of Competing Interest None., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Background: The association of sugar containing beverages (SCBs) with risk of breast, endometrial, ovarian and colorectal cancers is unclear. Therefore, we investigated these associations in the Canadian Study of Diet, Lifestyle, and Health., Methods: The study population comprised an age-stratified subcohort of 3185 women and 848, 161, 91 and 243 breast, endometrial, ovarian and colorectal cancer cases, respectively. We used Cox proportional hazards regression models modified for the case-cohort design to assess the associations of SCBs with risk of the aforementioned cancers., Results: Compared to SCB intake in the lowest tertile, SCB intake in the highest tertile was positively associated with endometrial cancer risk (HR T3 vs T1 = 1.58, 95 % CI = 1.08-2.33 and 1.78, 95 % CI = 1.12-2.81 for overall and Type 1 endometrial cancer, respectively) and ovarian cancer (HR T3 vs T1 = 1.76, 95 % CI: 1.09-2.83). Fruit juice intake was also positively associated with risk of Type 1endometrial (HR T3 vs T1 = 1.63, 95 % CI = 1.03-2.60). After excluding women with diabetes or cardiovascular diseases, we also observed sugar-sweetened beverages (SSBs) intake in the highest tertile was associated with higher risk of Type 1 endometrial cancer (HR T3 vs T1 = 1.65; 95 % CI: 1.03-2.64). None of the beverages was associated with risk of breast or colorectal cancer., Conclusion: We conclude that, in this cohort, relatively high SCB intake was associated with higher risk of endometrial and ovarian cancers, but not of breast or colorectal cancers. Our findings also suggest that relatively high SSB and fruit juice intake are associated with higher risk of Type 1 endometrial cancer., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Background: Although, biologically plausible evidence has implicated coffee, tea and caffeine with carcinogenesis, there is a paucity of data on their associations with risk of cancer among Canadian women. Hence, we assessed their associations with risk of breast, endometrial and ovarian cancers within this population., Methods: The study comprised a subcohort of 3185 women from a cohort of 39,532 female participants who completed self-administered lifestyle and dietary questionnaires at enrollment. During a median follow-up of approximately 12.2years, we ascertained 922, 180 and 104 breast, endometrial and ovarian cancer cases, respectively. We used Cox proportional hazards regression models modified for the case-cohort design to estimate the hazard ratios (HR) and 95% confidence intervals (CI) for the associations of coffee, tea and caffeine with risk of selected cancers., Results: Coffee, tea, and caffeine intake were not associated with overall risk of breast and ovarian cancers. There was, however, a tendency towards an increased risk of breast cancer with increasing levels of total coffee, caffeinated coffee and/or caffeine among premenopausal and normal weight women. Total coffee, caffeinated coffee, and caffeine were inversely associated with risk of endometrial cancer (HR per cup increase : 0.88; 95% CI: 0.79-0.95, HR per cup increase: 0.88; 95% CI: 0.80-0.96 and HR per 100mg increase: 0.93; 95% CI: 0.87-0.99, respectively)., Conclusion: Our findings suggest that coffee and/or caffeine may be associated with reduced risk of endometrial cancer but, probably, associated increased with risk of breast cancer among premenopausal or normal weight women. However, further studies are needed to confirm our findings., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Background: Evidence for a role of dietary risk factors in the cause of breast cancer has been inconsistent. The evaluation of overall dietary patterns instead of foods in isolation may better reflect the nature of true dietary exposure in a population., Objective: We used 2 cohort studies to identify and confirm associations between dietary patterns and breast cancer risk., Design: Dietary patterns were derived by using a principal components factor analysis in 1097 breast cancer cases and an age-stratified subcohort of 3320 women sampled from 39,532 female participants in the Canadian Study of Diet, Lifestyle and Health (CSDLH). We conducted a confirmatory factor analysis in 49,410 subjects in the National Breast Screening Study (NBSS) in whom 3659 cases of incident breast cancer developed. Cox regression models were used to estimate HRs for the association between derived dietary factors and risk of breast cancer in both cohorts., Results: The following 3 dietary factors were identified from the CSDLH: healthy, ethnic, and meat and potatoes. In the CSDLH, the healthy dietary pattern was associated with reduced risk of breast cancer (HR for high compared with low quintiles: 0.73; 95% CI: 0.58, 0.91; P-trend = 0.001), and the meat and potatoes dietary pattern was associated with increased risk in postmenopausal women only (HR for high compared with low quintiles: 1.26; 95% CI: 0.92, 1.73; P-trend = 0.043). In the NBSS, the association between the meat and potatoes pattern and postmenopausal breast cancer risk was confirmed (HR: 1.31; 95% CI: 0.98, 1.76; P-trend = 0.043), but there was no association between the healthy pattern and risk of breast cancer., Conclusion: Adherence to a plant-based diet that limits red meat intake may be associated with reduced risk of breast cancer, particularly in postmenopausal women., (© 2015 American Society for Nutrition.)

Background: Tobacco use has been implicated in the etiology of a large number of cancers, and there exists substantial biological plausibility that it could also be involved in breast carcinogenesis. Despite this, epidemiological evidence to date is inconsistent. The aim of this study was to investigate the role of active smoking and the risk of incident, invasive breast cancer using a prospective cohort of women from the Canadian Study of Diet, Lifestyle and Health., Methods: Using a case-cohort design, an age-stratified subcohort of 3314 women was created from 39,532 female participants who returned completed self-administered lifestyle and dietary questionnaires at baseline. A total of 1096 breast cancer cases were identified in the entire cohort (including 141 cases from the subcohort) by linkage to the Canadian Cancer Registry. Cox regression models were used to estimate hazard ratios for the association between the different smoking exposures and the risk of breast cancer, using a modification for the case-cohort design., Results: After carefully considering early-life exposures and potential confounders, we found no association between any smoking exposure and risk of breast cancer in this study (Hazard ratio=1.00, 95% confidence interval=0.87-1.17 for ever vs never smokers)., Conclusions: Although these results cannot rule out an association between smoking and breast cancer, they do agree with the current literature suggesting that, if an association does exist, it is relatively weak., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Background: Prostate cancer is a disease with a complex etiology. Oxidative stress has been implicated in its pathogenesis; however, few prospective studies have investigated the association between an oxidative stress/balance score and risk of prostate cancer., Methods: We investigated associations between an oxidative balance score, calculated as the summation of individual scores obtained from five pro-oxidative and eight anti-oxidative exposures, as well as each individual constituent of the score and risks of prostate cancer overall, and by clinical characteristics, in a case-cohort study (661 cases and 1864 subcohort) nested within the Canadian Study of Diet, Lifestyle, and Health cohort. Men in the lowest quintiles of each pro-oxidant exposure received a score of four (the highest score), while those in the highest quintile received a score of zero (the lowest score). In contrast, scoring for all anti-oxidants was performed in the opposite way. Total oxidative balance score was calculated by summating all individual scores of pro- and anti-oxidative variables, with higher values indicating a higher antioxidant status., Results: The average oxidative balance score was similar between prostate cancer cases and men in the subcohort: 25.2 and 25.3, respectively. There was no association between oxidative balance score and overall risk of prostate cancer with hazard ratios (HRs) of 1.00, 1.02, 1.03, 0.97 and 1.01 for increasing quintiles of the score (p-trend=0.71). There were also no associations for non-advanced or advanced disease, or when analysis was restricted to incident cases that arose after two years of follow-up (n=508). In general constituents of the score were not associated with prostate cancer, except for red meat intake (HR=1.44; 95%CI 1.06-1.95 comparing Q5 vs. Q1) and lycopene (HRs of 0.7-0.8 for increasing quintiles)., Conclusion: Our findings do not support an association between oxidative balance score and risks of overall prostate cancer or advanced disease., (Copyright © 2010 Elsevier Ltd. All rights reserved.)