Intakes of Calcium and Vitamin D and Breast Cancer Risk in Women

Abstract

Background: Animal data suggest the potential anticarcinogenic effects of calcium and vitamin D on breast cancer development. However, epidemiologic data relating calcium and vitamin D levels to breast cancer have been inconclusive.Methods: We prospectively evaluated total calcium and vitamin D intake in relation to breast cancer incidence among 10 578 premenopausal and 20 909 postmenopausal women 45 years or older who were free of cancer and cardiovascular disease at baseline in the Women's Health Study. Baseline dietary intake was assessed by a food frequency questionnaire. We used Cox proportional hazards regression to estimate hazard ratios and 95% confidence intervals.

Plasma 25‐hydroxyvitamin D and premenopausal breast cancer risk in a German case‐control study

“…7 Similar observations of an inverse association for total vitamin D intake in premenopausal but not postmenopausal women was also recently reported by the Women's Health Study. 15 One proposed explanation lies in the interaction of vitamin D and insulin-like growth factors, thus the potential of vitamin D to suppress IGFstimulated cell growth. 34,35 Because of the decline of IGF levels with age, the effect of vitamin D on IGF-related tumor development may be more pronounced in premenopausal compared to postmenopausal women.…”

“…Variables were entered as covariates in the logistic regression model if (i) including the covariate considerably changed the OR for the main variables of interest (>5% change in the ORs), (ii) if the covariate is a known or potential breast cancer risk factor or, (iii) if the covariate was likely to be associated with the main variable of interest (biological plausibility). OR estimates were both adjusted for time of blood collection in four categories, January-March, April-June, July-September, October-December only and with additional adjustment for first-degree family history of breast cancer (yes/no), number of births (0, 1-2, 3), duration of breast feeding (continuous, in months), age at menarche (<13, [13][14]15), BMI (continuous, in kg/m 2 ) and alcohol consumption (0, 1-18, 18 g ethanol/day). Age at first birth, smoking and education did not affect the estimates considerably and were therefore not included in the final model.…”

“…[1][2][3][4][5][6] Most of the epidemiologic studies regarding breast cancer risk have assessed the effects of vitamin D only for dietary intake yielding inconsistent results. [7][8][9][10][11][12][13][14][15] However, beside dietary intake, the main source of vitamin D is cutaneous production via sun exposure. Studies assessing the association of breast cancer risk and measures of sun exposure, as a proxy of endogenous vitamin D synthesis, have observed inverse associations.…”

Calcium intake and breast cancer risk: meta-analysis of prospective cohort studies

“…1. We included eleven studies (11)(12)(13)(15)(16)(17)(18)(19)(35)(36)(37) that fully met our inclusion criteria for this meta-analysis. The characteristics of the included studies are summarised in Table 1.…”

“…Dietary and lifestyle factors may have an important role in the development of breast cancer (2)(3)(4) , among which Ca intake has been suggested as a potential protective factor in mounting experimental research (5)(6)(7)(8)(9)(10) and several observational studies (11)(12)(13) . A metaanalysis by Chen et al (14) involving six prospective cohorts and nine case-control studies suggested a significant inverse association between Ca intake and risk of breast cancer, with a summary relative risk (RR) of 0·81 (95 % CI 0·72, 0·90) for the highest compared with the lowest intake of Ca, with a significant publication bias.…”