Does high-fat dairy consumption influence survival or risk of recurrence in breast cancer patients?

In this study, researchers investigated whether high-fat dairy products are linked to breast cancer recurrence (return of the cancer) in breast cancer patients.

High levels of estrogen (the main female sex hormone) represent one of the major causes of breast cancer. In Western cultures, most dairy cows have high estrogen content in their milk because they are pregnant while they are being milked. Because hormones, including estrogen, are found primarily in fat, it is thought that more estrogen is found in high-fat than low-fat dairy products. Although some studies have examined whether dairy consumption is linked to breast cancer, there is little known data on risk of breast cancer and the amount of fat found in dairy products. Researchers investigated whether high- or low-fat dairy consumption predicted the likelihood of breast cancer recurrence or survival among breast cancer patients.

Researchers used a pre-existing study group to conduct their study. 1893 patients previously diagnosed with and treated for early-stage breast cancer participated in this study. All participants were asked to complete dietary questionnaires at the start of the study and 6 years later. The questionnaire assessed overall, high-fat, and low-fat dairy consumption. Participants were followed for an average of 12 years. The researchers found that the consumption of high-fat dairy lowered survival rates for patients, including both overall (by 49%) and breast cancer-related (by 20%) survival. There was also a tendency for high-fat dairy to increase the likelihood of breast cancer recurrence, but this was not statistically significant. Researchers did not find an association between low-fat dairy products consumption and risk of recurrence or survival in this group of patients.

In summary, the consumption of high-fat dairy products was related in this study to a higher risk of recurrence and lower survival among breast cancer patients.