Numerous studies have attempted to link overall diet and lifestyle factors to breast cancer risk (see the overall diet tag). While some studies have found few or no statistically significant links, most have identified some factors associated with risk of breast cancer. Based on 35 studies published since 2013, the factors most often reported to be associated with increased breast cancer risk, in order of frequency, are alcohol use, consumption of red meat, obesity, lack of exercise or physical activity, consumption of animal fat or saturated fat, and consumption of energy-dense or sugary foods or drinks.

The factors most often reported to be associated with reduced breast cancer risk are diets high in fruits and/or vegetables, regular exercise or physical activity, consumption of fish or fatty fish, high fiber and/or whole grain consumption, high dietary carotenoid content, use of olive oil, and consumption of legumes, including soybeans. Now a new Dutch study has reported that modifiable risk factors are jointly responsible for approximately one quarter of postmenopausal breast cancer cases.

Latest research finds diet and lifestyle choices account for about 25% of cases

The study referenced at the beginning of this news story was designed to estimate the percentage of postmenopausal breast cancer cases in the Netherlands in 2010 attributable to diet and lifestyle choices. To conduct the study, the authors used existing data to calculate population attributle fractions (PAFs) of selected risk factors for breast cancer in women aged over 50 in 2010. PAF is the proportionate reduction in a population's disease (or death) that would occur if exposure to a given risk factor (e.g., alcohol use) were replaced by an ideal exposure scenario (e.g., no alcohol use). First, age-specific PAFs were calculated for each risk factor, based on previously-collected data, and the age-specific prevalence in the population (from national surveys) in 2000 (the analysis assumes a breast cancer latency period of 10 years). Age-specific PAFs were then summed in a weighted manner, using the 2010 age-specific breast cancer incidence rates as weights to calculate the overall PAF.

Among Dutch women over 40 in 2000, 51% were overweight or obese, 55% were physically inactive (defined as less than five days/week with 30 minutes of activity), 75% regularly consumed alcohol, 42% had ever smoked cigarettes, and 79% had a low dietary fiber intake (under 3.4 g/1000 kJ/day). These factors combined had a PAF of 25.7%, corresponding to 2,665 postmenopausal breast cancer cases in 2010. PAFs were 8.8% for overweight/obesity, 6.6% for alcohol consumption, 5.5% for physical inactivity, 4.6% for smoking and 3.2% for low fiber intake. The authors conclude that modifiable risk factors are jointly responsible for approximately one quarter of Dutch postmenopausal breast cancer cases, suggesting that the incidence of breast cancer could be lowered substantially by widespread adoption of a more healthy lifestyle.

Please see our articles on obesity, exercise, alcohol, and fiber for more information. Please also see our article on how to optimize your breast cancer diet for information on what to eat during all stages of treatment and recovery.