A new study published in the Journal of the National Cancer Institute shows that improving body weight, increasing exercise and reducing alcohol consumption can reduce a woman’s 20-year risk of breast cancer by more than 4 percent. The study included 2,569 cases and 2,588 controls with a follow-up period of 1991 to 1994. The researchers considered all risk factors and calculated the 10- and 20-year breast cancer risk, as well as the absolute 10- and 20-year risk reductions with maximal improvements in three controllable risk factors (weight, exercise, and alcohol consumption). The results showed that, from a population-wide perspective, the 20-year total breast cancer risk was reduced by 1.4% for women aged 45 years and by 1.6% for women aged 65 years by improving all three intervening risk factors simultaneously. The lower risk reductions in the older women were due to the fact that they usually had a combination of other non-interventional risk factors. On an individual basis, by improving all three controllable risk factors, the absolute 20-year risk reduction was 2.7% for a single 45-year-old woman with a positive family history of breast cancer and 3.2% for a single 65-year-old woman. An overall risk reduction of 1.6% would mean that 16,000 breast cancers would be avoided per year in 1 million women, but only 2,560 breast cancers would be avoided per million per year in postmenopausal women with a family history of breast cancer (8% of the population). Using the above model to calculate the absolute risk reduction could help further understand the potential benefits of breast cancer prevention programs, according to the researchers.