Association of Vitamin D and Calcium with Breast Cancer in Indian Women: Results of a Case-Control Study

The present case-control study was undertaken with the objective to study the association between nutritional risk factors and circulating concentrations of 25-hydroxyvitamin D [25(OH)D] and calcium with breast cancer (BC) risk in Indian women. A total of 320 women (cases) with confirmed BC attending a tertiary care hospital matched with 300 healthy women (controls) of similar age and socioeconomic status (SES) were included in the study. Information was collected from all of the study participants on sociodemographic status and dietary intake for vitamin D–containing foods by using a semistructured questionnaire. Blood samples (5 mL) were collected for the biochemical estimation of serum 25(OH)D concentrations by using a chemiluminescent immunoassay technique, and total serum calcium concentrations were determined by a colorimetric assay technique. Bivariate analysis was performed by univariate logistic regression, and multivariate analysis was performed by using stepwise multivariate logistic regression. The mean age of cases was 47.35 ± 10.2 y. Women from the low socioeconomic group had significantly higher odds of having BC (OR: 3.9; 95% CI: 1.8, 8.3) than did women from the high socioeconomic group (OR: 1.9; 95% CI: 1.0 to 3.5). Because of the presence of vitamin D in mushrooms and eggs, it was found that women with mushroom intake 1 to 2 times/mo had significantly lower odds of having BC (OR: 3.14; 95% CI: 0.7 to 13.2) than did women with occasional or no intake (OR: 5.47; 95% CI: 1.6 to 18.6). No significant association was found between the frequency of egg intake and the risk of BC. Serum concentrations of 25(OH)D and calcium <20 ng/mL and 10.5 mg/dL, respectively, were found to be significantly associated with a higher risk of BC, with ORs (95% CIs) of 1.78 (1.01, 3.17) and 1.73 (1.1, 2.64), respectively (P < 0.005). The results of the present study support the association in previous studies of lower 25(OH)D concentrations with an increased risk of BC.