Dairy intake in young people exerts no effect on overall breast cancer risk
Dairy consumption during adolescence or early adulthood does not appear to be associated with the overall risk of breast cancer, although results vary by hormone receptor status of tumours, a study has shown. Specifically, dairy intake is linked to higher ER–/PR– and lower ER+/PR+ cancer risk.
Researchers analysed early adulthood dairy consumption in relation to breast cancer risk in 90,503 premenopausal women aged 27–44 years. All women completed a validated food-frequency questionnaire. From 1991 to 2013, a total of 3,191 invasive breast cancer cases occurred. In the subgroup of 44,264 women who recalled adolescent dairy consumption in 1998, 1,318 invasive breast cancer cases were recorded.
Cox proportional hazard regression analysis showed no association between adolescent and early adulthood total dairy consumption and overall breast cancer risk (each serving/day during adolescence: total dairy hazard ratio [HR], 1.02; 95 percent CI, 0.97–1.07; each serving/day during early adulthood: total dairy HR, 1.01; 0.97–1.04). Breast cancer was not associated with intakes of calcium, vitamin D and lactose.
When analysis was stratified by oestrogen and progesterone receptor status, adolescent consumption of total and high-fat dairy was associated with increased risk of ER– and PR– tumours (each serving/day: total dairy HR, 1.11; 1.00–1.24; high-fat dairy HR, 1.17; 1.04–1.31).
On the other hand, higher adolescent high-fat dairy consumption was associated with lower risk of ER+ and PR+ tumours (each serving/day: high-fat HR, 0.91; 0.86–0.97).
The present data suggest that dairy intake in adolescence or early adulthood may not be an important predictor of breast cancer incidence, according to researchers. Additional studies are needed to explore the reported relationships, especially those between dairy intake and risk of breast cancers classified by hormone receptor status.