A diet high in saturated and total fats has been linked to a greater risk for developing specific types of breast cancers, including the most common tumorous growths driven by estrogen.

The wildly popular diet was associated with greater risk for breast cancers fuelled by the hormones estrogen and progesterone, as well as human epidermal growth factor 2 receptor-negative disease, or HER2 disease, according to researcher Sabrina Sieri, of Fondazione IRCCS Istituto Nazionale Dei Tumori in Milan.

The findings were published Wednesday in the Journal of the National Cancer Institute.

In the study, Sieri and her colleagues analyzed data from more than 10,000 breast cancer patients followed for about a dozen years after treatment. Those women had participated in the EPIC longitudinal study of 337,000 women living in 10 European countries. The diverse study group allowed researchers to compare the effects of dietary fat on women of varying genetic backgrounds.

To compensate for the limitations of self-reported data, the researchers conducted follow-up interviews by telephone with a random sampling of eight percent of those in the study group. Specifically, they found that a diet higher in total fat was associated with an increased risk of estrogen receptor-positive and progesterone receptor-positive cancers, while greater total and saturated fat consumption also increased the risk for HER2 disease.

“A high-fat diet increases [breast cancer] risk and, most conspicuously, that high saturated fat intake increases risk of receptor-positive disease, suggesting saturated fat involvement in the etiology of receptor-positive” breast cancer,” the authors wrote in the study.

Past attempts to study this association had yielded conflicting results as scientists had trouble collecting accurate dietary information from study volunteers who also tended to consume fat at similar levels within a given geographic area — making genetic comparisons less illuminating, Sieri says.

Such efforts to study breast cancer pathogenesis had also been hampered by problems with data collection related to the stratification of breast cancer into the three subtypes, each with its own prognosis and risk profiles, confounding many a researcher.

Estrogen-driven breast cancer is the most common type in the United States, accounting for some 60 percent of diagnoses, according to the Centers for Disease Control and Prevention.

 

Source: Sieri S, et al. Journal of the National Cancer Institute. 2014.