Re: High- and Low-Fat Dairy Intake, Recurrence, and Mortality After Breast Cancer Diagnosis

Extract

Kroenke et al. ( 1 ) recently reported positive associations between high-fat, but not low-fat, dairy consumption and all-cause and breast-cancer mortality in the Life After Cancer Epidemiology (LACE) cohort of women with early-stage breast cancer. The authors suggested that high-fat dairy intake may worsen breast cancer prognosis possibly through an increase in circulating estrogen levels.

To further investigate the issue, we used follow-up information until 2006 (median = 12.6 years) on 1453 women (aged 23–74 years) diagnosed with breast cancer between 1991 and 1994 who were previously enrolled in an Italian case–control study ( 2 ). Women were interviewed on their dietary habits before diagnosis using a validated food-frequency questionnaire ( 3 ). We considered whole milk, cheese, yogurt, ice cream, and desserts as high-fat dairy and part-skim/skim milk and ricotta/mozzarella cheese as low-fat dairy. Among 503 observed deaths, 398 were due to breast cancer. Hazard ratios (HRs) of death with 95% confidence intervals (CIs) were estimated using Cox proportional hazard models adjusted for age at diagnosis, geographical area, year of diagnosis, tumor stage, estrogen/progesterone receptor status, and potential confounders ( 2 ).