Breast cancer patients who eat high fat diary products may lower their survival chances from the disease years later, a new study has warned.
The study by US researchers is the first to examine the relationship between high-fat and low-fat dairy consumption following a diagnosis of breast cancer and long-term breast cancer survival.
Previous studies have shown that higher lifetime exposure to oestrogen is a causal pathway to breast cancer. Oestrogen levels are believed to be elevated in dairy products.
Oestrogenic hormones reside primarily in fat, so levels are higher in high-fat than in low-fat dairy products.
The researchers studied a cohort of women who were diagnosed with early-stage, invasive breast cancer between 1997 and 2000, primarily from Northern California region (83 per cent) and the Utah Cancer Registry (12 per cent).
Those consuming larger amounts of high-fat dairy (one serving or more per day) had "higher breast cancer mortality as well as higher all-cause mortality and higher non-breast cancer mortality," said lead researcher Candyce H Kroenke.
"Specifically, women consuming one or more servings per day of high-fat dairy had a 64 per cent higher risk of dying from any cause and a 49 per cent increased risk of dying from their breast cancer during the follow-up period," said Kroenke in a statement.
The category of high-fat dairy products researchers tracked included cream, whole milk, condensed or evaporated milk, pudding, ice cream, custard, flan, and also cheeses and yogurts that were not low-fat or non-fat.
In general, the women studied reported that they consumed low-fat milk and butter most often, and they consumed relatively limited amounts of low-fat dairy desserts, low-fat cheese and high-fat yogurt.
Overall, low-fat dairy intake was greater (median 0.8 servings per day) than high-fat dairy (median 0.5 servings per day), according to the study published in the Journal of the National Cancer Institute.
"High-fat dairy is generally not recommended as part of a healthy diet," said senior author Bette J Caan.
Of the total sample, 349 women had a recurrence of breast cancer and 372 died of any cause, 189 (50.8 per cent) of them from breast cancer.
