Dietary intake of vitamin D and calcium and breast cancer risk in the European Prospective Investigation into Cancer and Nutrition.
Abbas S., Linseisen J., Rohrmann S., Chang-Claude J., Peeters PH., Engel P., Brustad M., Lund E., Skeie G., Olsen A., Tjønneland A., Overvad K., Boutron-Ruault MC., Clavel-Chapelon F., Fagherazzi G., Kaaks R., Boeing H., Buijsse B., Adarakis G., Ouranos V., Trichopoulou A., Masala G., Krogh V., Mattiello A., Tumino R., Sacerdote C., Buckland G., Suárez MV., Sánchez MJ., Chirlaque MD., Barricarte A., Amiano P., Manjer J., Wirfält E., Lenner P., Sund M., Bueno-de-Mesquita HB., van Duijnhoven FJ., Khaw KT., Wareham N., Key TJ., Fedirko V., Romieu I., Gallo V., Norat T., Wark PA., Riboli E.
Studies assessing the effects of vitamin D or calcium intake on breast cancer risk have been inconclusive. Furthermore, few studies have evaluated them jointly. This study is the largest so far examining the association of dietary vitamin D and calcium intake with breast cancer risk in the European Prospective Investigation into Cancer and Nutrition. During a mean follow-up of 8.8 yr, 7760 incident invasive breast cancer cases were identified among 319,985 women. Multivariable Cox proportional hazards regression was used to estimate hazard ratios (HR) and 95% confidence intervals (CI) for pre- and postmenopausal breast cancer risk. Comparing the highest with the lowest quintile of vitamin D intake, HR and 95% CI were 1.07 (0.87-1.32) and 1.02 (0.90-1.16) for pre- and postmenopausal women, respectively. The corresponding HR and 95% CIs for calcium intake were 0.98 (0.80-1.19) and 0.90 (0.79-1.02), respectively. For calcium intake in postmenopausal women, the test for trend was borderline statistically significant (P(trend) = 0.05). There was no significant interaction between vitamin D and calcium intake and cancer risk (P(interaction) = 0.57 and 0.22 in pre- and postmenopausal women, respectively). In this large prospective cohort, we found no evidence for an association between dietary vitamin D or calcium intake and breast cancer risk.